Public Health Assessment

Transcription

1 Public Health Assessment Final Release PERFLUOROCHEMICAL CONTAMINATION IN SOUTHERN WASHINGTON COUNTY, NORTHERN DAKOTA COUNTY, AND SOUTHEASTERN RAMSEY COUNTY, MINNESOTA (Including: Woodbury, Cottage Grove, Newport, St. Paul Park, Afton, Grey Cloud Island Township, Denmark Township, South St. Paul, Hastings and Maplewood) EPA FACILITY ID: MN Prepared by the Minnesota Department of Health JANUARY 5, 2012 Prepared under a Cooperative Agreement with the U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Agency for Toxic Substances and Disease Registry Division of Health Assessment and Consultation Atlanta, Georgia 30333

2 THE ATSDR PUBLIC HEALTH ASSESSMENT: A NOTE OF EXPLANATION This Public Health Assessment was prepared by ATSDR s Cooperative Agreement Partner pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) section 104 (i)(6) (42 U.S.C (i)(6)), and in accordance with our implementing regulations (42 C.F.R. Part 90). In preparing this document, ATSDR s Cooperative Agreement Partner has collected relevant health data, environmental data, and community health concerns from the Environmental Protection Agency (EPA), state and local health and environmental agencies, the community, and potentially responsible parties, where appropriate. In addition, this document has previously been provided to EPA and the affected states in an initial release, as required by CERCLA section 104 (i)(6)(h) for their information and review. The revised document was released for a 30-day public comment period. Subsequent to the public comment period, ATSDR s Cooperative Agreement Partner addressed all public comments and revised or appended the document as appropriate. The public health assessment has now been reissued. This concludes the public health assessment process for this site, unless additional information is obtained by ATSDR s Cooperative Agreement Partner which, in the agency s opinion, indicates a need to revise or append the conclusions previously issued. Use of trade names is for identification only and does not constitute endorsement by the U.S. Department of Health and Human Services. Additional copies of this report are available from: National Technical Information Service, Springfield, Virginia (703) You May Contact ATSDR Toll Free at CDC-INFO or Visit our Home Page at:

3 Perfluorochemical Contamination in Southern Washington County, Northern Dakota County and Southeastern Ramsey County, Minnesota Final Release PUBLIC HEALTH ASSESSMENT PERFLUOROCHEMICAL CONTAMINATION IN SOUTHERN WASHINGTON COUNTY, NORTHERN DAKOTA COUNTY, AND SOUTHEASTERN RAMSEY COUNTY, MINNESOTA (Including: Woodbury, Cottage Grove, Newport, St. Paul Park, Afton, Grey Cloud Island Township, Denmark Township, South St. Paul, Hastings and Maplewood) EPA FACILITY ID: MND Prepared by: Minnesota Department of Health Under Cooperative Agreement with the U.S. Department of Health and Human Services Agency for Toxic Substances and Disease Registry

4 FOREWORD This document summarizes public health concerns related to a waste disposal site in Minnesota, and is a formal site evaluation prepared by the Minnesota Department of Health (MDH). For a formal site evaluation, a number of steps are necessary: Evaluating exposure: MDH scientists begin by reviewing available information about environmental conditions at the site. The first task is to find out how much contamination is present, where it is found on the site, and how people might be exposed to it. Usually, MDH does not collect its own environmental sampling data (although this case is an exception). Rather, MDH relies on information provided by the Minnesota Pollution Control Agency (MPCA), the Minnesota Department of Agriculture (MDA), the US Environmental Protection Agency (EPA), private businesses, and the general public. Evaluating health effects: If there is evidence that people are being exposed or could be exposed to environmental contaminants, MDH scientists will take steps to determine whether that exposure could be harmful to human health. MDH s report focuses on public health that is, the health impact on the community as a whole. The report is based on existing scientific information. Developing recommendations: In this report, MDH outlines conclusions regarding any potential health threat posed by a site and offers recommendations for reducing or eliminating human exposure to pollutants. The role of MDH is primarily advisory. For that reason, the evaluation report will typically recommend actions to be taken by other agencies including EPA and MPCA. If, however, an immediate health threat exists, MDH will issue a public health advisory to warn people of the danger and will work to resolve the problem. Soliciting community input: The evaluation process is interactive. MDH starts by soliciting and evaluating information from various government agencies, the individuals or organizations responsible for the site, and community members living near the site. Any conclusions about the site are shared with the individuals, groups, and organizations that provided the information. Once an evaluation report has been prepared, MDH seeks feedback from the public. If you have questions or comments about this report, we encourage you to contact us. Please write to: OR call us at: On the web: Community Relations Coordinator Site Assessment and Consultation Unit Minnesota Department of Health 625 North Robert Street / P.O. Box St. Paul, MN (651) or (toll free call - press "4" on your touch tone phone) 2

5 Table of Contents FOREWORD... 2 Table of Contents... 3 Summary... 4 Introduction... 7 Background M-Woodbury Disposal Site Description and History... 9 Geology / Hydrogeology PFC Analysis Evaluation of PFCs in Drinking Water Municipal and Non-municipal Community Well Monitoring Private Well Sampling PFC-Related Investigations at the 3M-Woodbury Disposal Site MPCA 3M Consent Order for PFC Disposal Sites Remedial Options for the 3M-Woodbury Disposal Site Site Visits Demographics, Land Use, and Natural Resources General Regional Issues Community Concerns Evaluation of Environmental Fate and Exposure Pathways Introduction Environmental Fate Evaluation of Impacts on Groundwater Exposure through Private Wells Exposure through Public Water Supplies Exposure through other Pathways Public Health Implications of PFC Exposure Summary of Toxicological Information Summary of Human Exposure Information Discussion of the Public Health Implications of PFC Exposure Health Outcome Data Review Child Health Considerations Conclusions Recommendations Public Health Action Plan References REPORT PREPARATION Glossary Appendices Appendix 1: Figures Appendix 2: Tables Appendix 3: Public Comments 3

6 Summary INTRODUCTION The Minnesota Department of Health s (MDH) mission is to protect, maintain, and improve the health of all Minnesotans. For communities affected by perfluorochemicals (PFCs) in their drinking water, MDH s goal is to protect people s health by providing health information the community needs to take actions to protect their health. MDH also monitors public water supplies for PFCs, and advises the MPCA on actions that can be taken to protect public health. PFC-containing wastes were disposed of by 3M Corporation (3M) in land disposal sites in Oakdale, Lake Elmo, and Woodbury, Minnesota and at their manufacturing facility in Cottage Grove, Minnesota. This report focuses on the Woodbury disposal site and surrounding affected communities south of Interstate 94, where PFCs from all four sites have contributed to groundwater contamination. In the past, people may have been exposed to air emissions during the handling, disposal, or burning of waste at the disposal sites. People also may have come into direct contact with the waste or contaminated soils if they entered the sites. However, these exposure pathways appear to have been addressed by site cleanup activities. PFCs were released to the groundwater from the disposal sites, resulting in contamination of nearby public and private drinking water wells. PFCs continue to be detected in public and private wells across a wide area of south Washington County, and in parts of northern Dakota County and southeastern Ramsey County. Twenty-four private wells in the area covered by this report have PFC concentrations that exceed MDH health-based drinking water exposure limits and those homeowners have been provided treatment or bottled water to reduce exposure. PFCs in all other wells, public and private, are below MDH exposure limits. OVERVIEW CONCLUSION 1 BASIS FOR DECISION MDH reached three important conclusions in this Public Health Assessment. MDH cannot conclude whether drinking or breathing PFCs in water or air or contact with PFC-containing wastes in the past harmed people s health. No information is available regarding past levels of PFCs in the water or air of the affected communities. Similarly, no information is available regarding what, if any, PFC waste people may have encountered if they entered the 3M-Woodbury Disposal Site in the past. As a result, it is not possible to determine the level of PFCs to which people may have been exposed in the past. Biomonitoring studies of residents in Oakdale, Lake Elmo, and Cottage Grove indicated that levels of PFCs in their blood are above national averages, but have fallen due to the 4

7 provision of treated drinking water to residents previously exposed to PFCs above Minnesota standards. While available evidence suggests that the measured PFC levels are unlikely to cause adverse health effects, there is no information available regarding past PFC levels in resident s blood and whether those past levels would have resulted in adverse health effects. NEXT STEPS CONCLUSION 2 Although nothing can be done to alter past exposures, MDH will continue to provide health information regarding PFCs to the affected communities, as it becomes available. MDH concludes that currently, drinking water from public or private wells that contain PFCs is not expected to harm people s health. BASIS FOR Current exposures to PFCs are below health-based exposure limits because DECISION bottled water or whole-house activated carbon filters have been provided at 24 homes that were issued a drinking water well advisory by MDH, although such filters are not considered by MDH to be the best, long-term solution if other sources of water are available. No one currently is drinking water that has PFCs at levels above MDH health-based exposure limits. Remediation actions to address PFCs at the waste disposal sites are currently being implemented by 3M and the MPCA. NEXT STEPS 3M should continue to follow the requirements of the Consent Order to implement the selected remediation options for soil and groundwater at the 3M-Woodbury Disposal Site. Although site cleanup actions have reduced or eliminated PFC contamination in surface soils at the 3M-Woodbury Disposal Site, people should avoid trespassing on the property. 3M should improve and maintain the existing fencing of the site, particularly along the south boundary, to prevent trespassing. Extensions of the Cottage Grove municipal water supply to serve areas where private wells contain levels of PFCs in excess of MDH HRLs should be considered. Monitoring of selected private wells in the affected area should continue, under MDH and MPCA approved sampling plans, as needed to track changes in the plume and monitor for changes in concentration in individual wells. MPCA should ensure that there is an adequate monitoring well network at the disposal site to provide sufficient information regarding water quality in the high transmissivity zone of the Prairie du Chien aquifer. CONCLUSION 3 Treatment of city and private wells that exceed MDH HRLs or cumulative drinking water guidelines has reduced or eliminated PFC exposure for the users of those wells and resulted in decreased average concentrations of PFCs in the blood of those users. 5

8 BASIS FOR CONCLUSION NEXT STEPS FOR MORE INFORMATION Monitoring of treated water at the City of Oakdale and in private residences where GAC filter systems were installed demonstrate removal of PFCs to below laboratory reporting limits. Biomonitoring of PFCs in the blood of Oakdale, Lake Elmo, and Cottage Grove residents previously exposed to PFCs through their drinking water, but now drinking treated city or private well water, demonstrated significant reductions in blood levels of PFCs between 2008 and The MPCA will continue to monitor and maintain whole-house granular activated carbon (GAC) filter systems in homes where the well water exceeds MDH HRLs or cumulative drinking water guidelines. MDH will continue to work with the City of Oakdale and 3M to ensure proper treatment of city wells that exceed MDH HRLs. MDH will consult with its Scientific Advisory Board regarding possible future biomonitoring in the affected communities, if funding is available. If you have concerns about your health, you should contact your health care provider. You may also call MDH at or (press #4) and ask for information on PFCs. You may also visit our PFC Web site at 6

9 Introduction The 3M Company (3M; formerly Minnesota Mining and Manufacturing Company) began research and development of perfluorochemicals (PFCs) at its Cottage Grove, Minnesota facility in southern Washington County, Minnesota in the late 1940s. Commercial production of eight-carbon PFC compounds, including perfluorooctanoic acid (PFOA) and precursors for perfluoro-octane sulfonate (PFOS) and PFOA, occurred from the early 1950s until Production of the four-carbon compound, perfluorobutanoic acid (PFBA) ceased in M currently produces perfluorobutane sulfonate (PFBS)-based products which are substitutes for the earlier eight-carbon PFCs. PFBS is also a fourcarbon compound. In addition, 3M continues to use and/or produce one- to three-carbon perfluoroalkyl substances at the Cottage Grove facility (3M, 2010a). MDH prepared a Health Consultation focusing on PFC releases at the Cottage Grove facility (MDH, 2005). Until the 1970 s, wastes from the facility, including electrofluorochemical PFC production process wastes such as production wastes and wastewater treatment plant sludge, were disposed of at the Cottage Grove facility and several known disposal sites identified by 3M in Washington County (Weston, 2005). In the early 1970 s, 3M built an on-site incinerator where wastes were processed; since the mid-1970 s the incinerator ash and scrubber sludge have been disposed off-site in an industrial waste landfill. The types of wastes disposed of at these sites and the estimated time of the disposal are listed below: Disposal Facilities in Washington County that Received 3M Wastes Disposal Facility Waste Disposed Estimated Dates 3M-Oakdale Disposal Site Liquid and solid industrial waste M-Woodbury Disposal Site Liquid and solid industrial waste Washington County Landfill, Wastewater treatment plant sludge, Lake Elmo incinerator scrubber sludge and ash, iron oxide sludge 3M-Cottage Grove Facility Industrial wastes, ash, sludge 1950s 1970s The general locations of the above disposal sites, along with the 3M Cottage Grove facility are shown in Figure 1 (all figures can be found in Appendix 1). PFCs disposed of at the sites identified in the table above have impacted soil, groundwater, surface water, sediments, biota, and nearby drinking water wells, both public and private, in large areas of the affected communities covered by this report. Figure 1 also includes the Pigs Eye Dump site in St. Paul. 3M reported sending incinerator ash to this site in 1971, although the more likely source for the PFCs are the municipal incinerator ash and solid waste disposed of at the dump. It is not included in the Consent Order agreement between 3M and the MPCA (see below), but is included in the figure because high levels of PFCs have been detected in groundwater and surface 7

10 water at the site and it is located within the area covered by this report. However, PFCs at that site have not affected nearby drinking water wells. Although the 3M-Woodbury Disposal Site is not on the National Priorities List (NPL), MDH has prepared this report in response to requests from the MPCA, Washington County, local communities, and citizens to: summarize current conditions in southern Washington County, northern Dakota County, and southeastern Ramsey County relative to the PFC contamination; evaluate the potential health risks associated with the use of drinking water impacted by PFCs, especially in public water supplies; provide the public with an opportunity to comment on the public health actions taken to date; and provide recommendations to protect public health in the future. MDH has consulted with staff from the U.S. Environmental Protection Agency (EPA), MPCA, Washington County, the cities of Woodbury, Cottage Grove, Hastings, St. Paul Park, and other local governments in the affected area, community members, and 3M to gather information for this report. MDH prepared a separate report focusing on the PFC releases at the 3M-Oakdale Disposal Site and Washington County Landfill and the affected surrounding communities north of Interstate 94 (I-94). Investigations in those communities revealed that PFBA from the two sites co-mingled in places to create a large plume of groundwater contamination that extended to, and likely beyond, I-94 (MDH, 2008a). This report evaluates PFC contamination in the affected communities south of I-94; while it focuses mainly on the 3M-Woodbury Disposal Site, this report also evaluates the overall PFC impacts to these communities, including those from the PFC plumes emerging from the Oakdale and Lake Elmo disposal sites and migrating south of I-94. Perfluorochemicals, broadly speaking, are a class of organic chemicals in which fluorine atoms completely replace the hydrogen atoms that are typically attached to the carbon backbone of organic hydrocarbon molecules. The PFCs that are the subject of this report are characterized by such a perfluorinated carbon chain with a functional end group (Figure 2). Because of the very high strength of the carbon-fluorine bond, PFCs are inherently stable, nonreactive, and resistant to degradation (3M, 1999a). PFCs made by 3M at its Cottage Grove facility were used in the manufacture of a variety of commercial and industrial products by 3M and other companies, including fabric coatings (such as Scotchgard TM ), surfactants, non-stick products (including Teflon TM ), fire-fighting foams, film coatings, and other products. The unique physical and chemical properties of many PFCs allow them to move easily through the environment (EPA, 2002; OECD, 2002; ATSDR, 2009). As a result, they have been found globally at low levels. Some PFCs are bio-accumulative (i.e., build up in living organisms) and one PFC, perfluorooctane sulfonate (PFOS) has been detected in the blood and tissues of humans and animals from virtually all parts of the world. It should be noted that while the use of PFCs has been restricted in the United States by the 8

11 EPA to certain products for which there is no adequate substitute, they are still manufactured and used in other countries around the world, including Italy, Russia, China, Japan, and Korea. Toxicological research on PFCs is ongoing in government, industry and academia. Published studies show that animal exposure to PFCs at high concentrations adversely affects the liver and other organs (ATSDR, 2009). The mechanisms of toxicity are not entirely clear; one likely major mechanism involves effects on certain enzymes regulating metabolic pathways in the liver. Exposure to high concentrations of one PFC, perfluorooctanoic acid (PFOA) over long durations has been shown to cause tumors in some test animals, although the specific mechanisms are not clear and the relevance to humans may be low. Developmental effects have also been observed in the offspring of pregnant rats and mice exposed to high doses of PFOA and PFOS. Background 3M-Woodbury Disposal Site Description and History The 656-acre 3M property that contains the 40-acre 3M-Woodbury Disposal Site straddles the border of Woodbury and Cottage Grove (see Figure 3). The actual waste disposal areas are located in Woodbury and consist of two areas referred to as the Main Disposal Area (approximately ten acres) and the Northeast Disposal Area (approximately five acres; Weston, 2007a). Prior to 1960, industrial waste generated at the 3M manufacturing plants located in Cottage Grove and downtown St. Paul were hauled and disposed of by a private waste hauler at a property located in Oakdale (now referred to as the 3M-Oakdale Disposal Site). Following the owner s death in 1959, 3M contracted with St. Paul Terminal Warehouse, who continued to haul and dispose of material on the 3M-Oakdale Disposal site property. In 1960, St. Paul Terminal Warehouse purchase 240 acres of farmland in Woodbury for use as a waste disposal site. In 1960, 3M signed a contract with St. Paul Terminal Warehouse for disposal of wastes at the new Woodbury site. In 1961, 3M purchased the land and continued to use the site to dispose of liquid and solid industrial wastes (solvents, tapes, plastics, and resins) generated at their Cottage Grove and downtown St. Paul facilities. 3M is believed to be the only company to have used the Woodbury site for industrial waste disposal. The wastes were buried in clay-lined trenches. In addition, municipal wastes from the cities of Woodbury and Cottage Grove were disposed of in two separate areas of the site (approximately five acres total) from (Weston, 2008a). Groundwater contamination at the site was first detected in 1966 when volatile organic compounds (VOCs, mostly solvents) were found in groundwater monitoring wells on the site and a private well located immediately west of the site. The first wells for a 9

12 groundwater extraction (barrier well) system were installed by 3M in 1967 and by 1973 the system consisted of four wells which have operated continuously since. The extracted groundwater is pumped via a pipeline to the 3M Cottage Grove manufacturing plant, where it is used as cooling or process water and then discharged to the Mississippi River under an NPDES permit issued by the MPCA. Additional cleanup measures were taken at the site to consolidate and burn wastes, with the goal of reducing sources of VOC contamination to the groundwater. Approximately 200,000 cubic yards of wastes were excavated from the Main Disposal Area and burned on-site in February of The remaining ash and waste were consolidated and reburied in the Main Disposal Area trenches. In 1992, 3M entered the site into the MPCA s Voluntary Investigation and Cleanup (VIC) program, under which additional investigation and response actions were taken to further address contamination at the site. A 1994 report of that work noted that fluorochemical wastes had been disposed of and were present in soil and soil gases at the site, but analytical methods were not sensitive enough at that time to detect PFCs in the groundwater (3M, 1994). In 1996, 3M backfilled open areas and regraded the site, placed a cap consisting of a minimum of 24 inches of clean soil over the former disposal areas, and filed an institutional control on the property deed to restrict future land use at the property. Geology / Hydrogeology The geology of the region where the 3M-Woodbury Disposal Site is located consists of glacial drift and alluvial sediments (stratified sand, silt, and clay deposited by glaciers and rivers, respectively) overlying a thick sequence of Paleozoic sedimentary rock formations made up of sandstone, limestone, dolomite, and shale. These, in turn, overlay pre-cambrian volcanic rock formations composed primarily of basalt. The bedrock formations tilt and thicken slightly to the south and west, forming the eastern rim of a large geologic structure known as the Twin Cities Basin. Figure 4 shows the sequence of bedrock units in south Washington County. The geology of this area has been extensively studied by the Minnesota Geological Survey and others (Tipping et al., 2006; Runkel et al., 2003; MGS, 1990). Before the glacial drift and alluvial sediments were deposited, streams eroded deep valleys into the surface of the bedrock. In some places the valleys cut down to the Jordan Sandstone. The valleys were later filled with glacial and alluvial sediments, leaving little or no evidence at the surface of their presence below, except for a series of elongated lakes in Lake Elmo and a deep ravine in southern Cottage Grove. Figure 1 shows the location of a major bedrock valley that extends from Lake Elmo south to the Mississippi River valley. The bedrock valleys in south Washington County provide pathways that allow contaminants in the groundwater to enter deeper aquifers more rapidly than would be the case if the bedrock layers were intact. The bedrock valley shown in Figure 1 is present beneath the west side of the site. As the valley was eroded, successively deeper bedrock formations were exposed from east to 10

13 west. As a result, the uppermost bedrock layer in the northeastern portion of the site is the Platteville Limestone, while in the center of the site it is the St. Peter Sandstone, and on the west side it is the Prairie du Chien Group dolomite and Jordan Sandstone (see Figure 5). The bedrock in southern Washington County also has been altered by major faults (fractures in the rock along which movement has occurred, see Figure 1). In some places, bedrock units on either side of such faults have been displaced vertically as much as 150 feet. This means that in some parts of the investigation area, one geologic formation may be in direct contact with another (see Figure 4). This may allow groundwater and contaminants to move between aquifers that might not otherwise be connected. It also means that two wells of similar depth and separated by a distance of only a few hundred feet may draw water from completely different formations. Regional groundwater flow in the area of the site is further complicated by the presence of two major regional groundwater discharge features, the Mississippi and St. Croix Rivers. In general, groundwater in the east half of Washington County flows toward and discharges to the St. Croix River, while groundwater in the west half of the county flows toward and discharges to the Mississippi River. The zone where this divergence of the groundwater flow occurs is often referred to as a groundwater divide (Figure 1). While similar in concept to the better known continental divide (that separates rivers that flow east to the Atlantic Ocean from those that flow west to the Pacific Ocean), a groundwater divide is less fixed and may shift its location as a result in changes in climate and pumping of groundwater. As a result, the location of the actual groundwater divide is approximate, will change over time, and may be slightly different in each aquifer. In southern Washington County, the groundwater divide is located somewhere near or under the east side of the 3M-Woodbury Disposal Site (Kanivetsky and Cleland, 1990). This means that groundwater contaminants beneath eastern portions of the site could move east-southeast toward the St. Croix River while those beneath western portions of the site would more likely move west-southwest toward the Mississippi River. Additionally, in Denmark Township and southeast Cottage Grove, near where the two rivers converge, the regional groundwater flow direction fans out. The result is that contaminants released to the groundwater in this area could potentially affect a larger area than is typically seen at most sites. The type of geologic units beneath the disposal site also affects how groundwater and contaminants move. The sand and gravel deposits in the buried bedrock valley, and the Platteville, St. Peter and Prairie du Chien formations beneath the site are highly permeable, allowing groundwater to easily move downward through pore spaces between sand grains and along fractures. There are four major drinking water aquifers in the investigation area, that are from shallowest to deepest: St. Peter Sandstone, Prairie du Chien Group, Jordan Sandstone, and Franconia Sandstone (Figure 4). State well records also indicate there are some wells using the overlying sand and gravel deposits, but this appears to be rare. All of the 11

14 municipal water supply wells in the affected communities draw water from the Jordan Sandstone. Groundwater in the St. Peter migrates primarily through the pore spaces between the sand grains, although fractures and solution cavities are present in the St. Peter, particularly near the buried bedrock valleys (Alexander, 2007; Runkel et al., 2007). Such solution cavities may create pathways through which groundwater and contaminants migrate more quickly than is typically observed in the St. Peter. Groundwater flow in the Prairie du Chien dolomite is heavily influenced by fractures (cracks and voids) in the formation. The Prairie du Chien is actually considered a group composed of two separate dolomite formations referred to as the Shakopee and the Oneota members of the Prairie du Chien Group. For general purposes, this report will consider the Prairie du Chien Group as a single unit. However, it is useful to note that although the rock itself in the lower Oneota formation tends to be more massive (i.e. denser, with little pore space) than the sandier overlying Shakopee formation, the Oneota tends to have more solution cavities. As a result, the Oneota provides the higher yield of water to wells (Lindholm et al., 1974). Hydraulic conductivity is a measure of how much water can pass through an aquifer, and depends not only on the amount of pore space that water can pass through (the aquifer s porosity), but how well connected those pore spaces are to one another (the aquifer s permeability). The hydraulic conductivity of similar fractured bedrock groundwater systems in southeast Minnesota has been shown to sometimes exceed several thousand feet per day (Runkel et al., 2007). Tipping et al. (2006) identified a zone referred to as the high transmissivity zone - near the contact of the Shakopee and Oneota members of the Prairie du Chien which has densely spaced fractures - this create a horizon where groundwater flow rates are very high. In fact, pumping of wells that pull water from that horizon can even result in upward flow of groundwater from the underlying Jordan aquifer (Tipping et al., 2006). Below the Prairie du Chien is the Jordan Sandstone. Although the lower Oneota formation of the Prairie du Chien group may limit downward migration of groundwater from the Prairie du Chien to the Jordan (Tipping et al., 2006), pumping wells in the Jordan can cause groundwater to move downward from the Prairie du Chien into the Jordan. Preliminary modeling of groundwater flow by MDH suggests that groundwater flow from the Prairie du Chien to the Jordan may be occurring primarily in the areas immediately around municipal wells as a result of the high pumping rates of those wells (A. Djerrari, MDH, personal communication, 2007). Beneath the Jordan Sandstone is the St. Lawrence formation, composed of dolomite and siltstone. This formation is not considered an aquifer but rather a confining unit because it has low vertical permeability, so groundwater generally does not move downward through it. This means that in most areas, the St. Lawrence protects the aquifers beneath it from downward migration of contaminants. Below the St. Lawrence formation, in descending order, are the Franconia, Ironton, and Galesville sandstone aquifers (which are often considered to be one single aquifer), the Eau Claire confining unit, and the Mount Simon sandstone aquifer. 12

15 Under natural conditions, the top of the water table at the 3M-Woodbury Disposal Site is located approximately feet below the ground surface. The large volumes of water (an average of 4.6 million gallons per day) being removed by the groundwater containment system at the site has lowered the water table, especially near the pump-out wells, so that the depth to the top of the water table is now between feet below ground. PFC Analysis In late 2003, the MDH Public Health Laboratory developed the capability to analyze water samples for two PFCs, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). These two PFCs have been the focus of the majority of the scientific research on perfluorochemicals. PFOA and PFOS accumulate in humans and other species (EPA 2002, OECD 2002). PFOS, but not PFOA, has been shown to bioaccumulate in fish. Both have been found to be widespread in the environment. PFOA was produced at the 3M-Cottage Grove plant on a large scale; some PFOS production or use also reportedly occurred, although most of the eight-carbon fluorosulfonate production involved chemical precursors to PFOS (MDH, 2005). Eightcarbon fluorocarbon production at the site was phased out in In the spring of 2006, the MDH Public Health Laboratory expanded their PFC method to include a total of seven PFCs. This was done in response to a request from the MPCA in late 2005 following the detection of other PFCs in soil and water samples collected by the MPCA at the former Washington County Sanitary Landfill and analyzed by a laboratory in British Columbia, Canada (Axys Analytical Services). The seven PFCs currently being analyzed in water by MDH are: PFBA : Perfluorobutanoic acid PFPeA : Perfluoropentanoic acid PFHxA : Perfluorohexanoic acid PFOA : Perfluorooctanoic acid PFBS : Perfluorobutane sulfonate PFHxS : Perfluorohexane sulfonate PFOS : Perfluorooctane sulfonate Water samples are collected in clean 250 milliliter polyethylene bottles. Care is taken to avoid the use of products that could contain PFCs during sampling. The analysis is conducted using a combined high-pressure liquid chromatography tandem mass spectrometry (LC/MS/MS) method, using radio-labeled PFOA and PFOS standards. Each sample is spiked in the lab with a known quantity of labeled standard. The recovery rate of the added standard must be within ± 30% of the known labeled standard concentration added to the sample to meet quality control requirements. In September 2007, the MDH Public Health Laboratory (PHL) issued new, lower reporting levels for the seven PFCs of 0.3 parts per billion (ppb), or 300 parts per trillion (ppt) in water (P. Swedenborg, PHL, personal communication, 2007). The reporting level is the concentration at or above which the laboratory can consistently detect and quantify PFCs with a high level of 13

16 certainty. PFCs detected at concentrations between 50 and 300 ppt are reported as estimated, or J flagged values, which have slightly less certainty than those at or above the reporting level. The MDH PHL has the capability to detect and quantify PFC concentrations at levels below 50 ppt, but with even less certainty in the quantification. Evaluation of PFCs in Drinking Water MDH has established Health Risk Limits (HRLs) in Minnesota Rules of 0.3 ppb for both PFOS and PFOA. The HRL represents the level of a contaminant in groundwater that MDH considers safe for daily human consumption over a lifetime. The HRLs are protective for adults, children, and developing fetuses, and in the case of PFCs are based on non-cancer effects. In February 2008, MDH established a Health Based Value (HBV) for PFBA of 7 ppb, based, in part, on toxicological and pharmacokinetic studies completed in late 2007 by EPA and 3M. A HBV is a criterion that is established using the same risk assessment procedures and policies used for HRLs, but that has not yet been promulgated through rulemaking. MDH develops HBVs when Minnesota agencies need guidance for chemicals that do not have HRLs. MDH may also calculate HBVs to update an existing value if there is significant new scientific information for the chemical and/or to apply new risk assessment methods. HBVs may be used by the public, state and local risk managers, and other stakeholders to assist in evaluating potential health risks to humans from exposures to a chemical. In general, MDH anticipates that HBVs for water will become HRLs at the time that MDH next amends the Health Risk Limits for Groundwater rule. Information on MDH HRLs and HBVs, including the specific methodology, exposure assumptions, and references, is available at Because specific information on PFBA toxicity needed to develop a HBV was lacking, MDH could not establish a HBV for PFBA before February 2008 (see Therefore, as a cautious public health approach, prior to the issuance of the HBV for PFBA MDH used a level of 1 ppb as a point of departure for offering advice to private well owners about reducing exposure to PFBA. In other words, MDH was confident that exposure to PFBA in drinking water at levels below 1 ppb was unlikely to be of health concern. Because MDH could not quantify the potential health risk at levels above 1 ppb, advice was provided to those private well owners (or community water supply customers) on how to reduce their exposure if they chose. The available scientific information for the four remaining PFCs that MDH currently analyzes for is more limited than the information available for PFOS, PFOA, or PFBA. Based on their chemical characteristics, it is anticipated that research will show that PFPeA and PFHxA are generally less toxic than PFOA and, like PFBA, have a short halflife. PFBS and PFHxS have been studied more extensively. PFHxS in particular is known to have a long half-life in humans (see below). MDH has reviewed the available toxicological information on PFBS and PFHxS, and recently established an HBV for PFBS of 7 ppb (see MDH staff determined that there was insufficient information to establish an HBV for PFHxS. 14

17 HRLs and HBVs are used by MDH to determine if a drinking water well advisory is warranted for an individual well. The MPCA uses MDH advisories to take actions to protect public health from long-term exposure to PFCs, such as providing bottled water or individual water treatment. In cases where a combination of PFOS, PFOA, and PFBA (or other chemicals with similar toxicological endpoints) are present, but do not exceed their individual HRLs or HBV, MDH calculates a Hazard Index to account for possible effects of exposure to more than one PFC at a time. The Hazard Index is the sum of the ratios of the concentrations of PFOS and PFOA over their individual HRLs, and PFBA over its HBV. If the Hazard Index exceeds a value of one, a drinking water well advisory is issued. Municipal and Non-municipal Community Well Monitoring 1 In late 2004, after releases of PFCs were documented at the 3M-Cottage Grove facility (later described in MDH 2005), 3M collected samples from municipal wells in Cottage Grove and Hastings for analysis for PFOS and PFOA. The samples, collected under the supervision of MDH and city staff, were sent to 3M s contract laboratory, Exygen Research (now MPI) in State College, Pennsylvania, for analysis. Neither PFOS nor PFOA were detected in the eleven Cottage Grove municipal wells. A trace of PFOA (defined as between 25 and 50 ppt) was detected in one of five Hastings municipal wells. In mid-2006, the MDH Public Health Laboratory expanded the list of PFCs for analysis and lowered the analytical detection limits as described previously. Low levels of PFBA (0.1 to 0.3 ppb) were detected in several Woodbury municipal wells during routine sampling. No other PFCs were detected. By fall of 2006, it was found that low levels (0.1 to 0.5 ppb) of PFBA were present in all 16 Woodbury municipal wells. The presence of PFBA in those wells appeared to be the result of PFCs moving away from the disposal sites used by 3M in Oakdale and Lake Elmo (MDH, 2008). The city of Cottage Grove requested that their municipal wells be re-tested for PFCs using the expanded PFC list. In December 2006, PFBA was detected in all of the Cottage Grove municipal wells at concentrations ranging from 0.3 to 1.5 ppb. The detection of PFBA at concentrations higher than those found in the Woodbury municipal wells suggested that the PFCs in the Cottage Grove city wells were from another source, such as the 3M-Woodbury Disposal Site, located in or near Cottage Grove, rather than the 3M-Oakdale Disposal Site and Washington County Landfill. The detections of PFBA in municipal wells in Woodbury and Cottage Grove triggered sampling of other municipal and community wells in south Washington and northern Dakota Counties to determine if they had been impacted by PFCs, beginning in January This sampling eventually included Woodbury, Cottage Grove, Newport, St. Paul Park, Hastings and South St. Paul; PFBA was detected in some or all of the municipal wells in each of these cities. Low levels (0.44 ppb on average) of PFBA were also found in a non-municipal community water supply well serving a housing development in 1 Community wells are those that serve at least 25 people or 15 service connections. Municipal community wells are owned and operated by incorporated municipal governments; non-municipal community wells may be owned and operated by a homeowners association, manufactured mobile home park, etc. 15

18 Cottage Grove known as Eagles Watch, in the eastern part of the city. Sampling was conducted on a monthly basis in 2007 to determine if the levels of PFBA were changing. Sampling frequency changed from monthly to quarterly in 2008 when it became apparent that the levels were stable or even declining slightly. The median, average and range of concentrations of PFBA detected in the affected wells serving each community s water supply system from June 2006 through December 2010 are shown in the table on page 15. PFBA is the only PFC that has been detected in municipal wells in Newport and South St. Paul. Low levels of PFBS (up to 0.32 ppb) and PFHxS (up to 0.16 ppb) have been consistently detected in three Cottage Grove municipal wells; trace amounts of PFPeA and PFHxA (less than 0.1 ppb) have also been intermittently detected in various Cottage Grove municipal wells (see Table 4, Appendix 2). PFOA has been intermittently detected at approximately 0.05 ppb in one Hastings municipal well and one St. Paul Park municipal well. In Woodbury, PFHxS has been intermittently detected at approximately 0.05 ppb in one well, and PFOA was detected once at 0.05 ppb in one municipal well. Municipal Well PFBA Data, June 2006 Dec City No. of Comm. Wells No. of Comm. Wells w/pfba Range of PFBA (ppb) Median of all Results (ppb) Cottage Grove Hastings 5 5 ND Newport St. Paul Park So. St. Paul 5 3 ND Woodbury ND NOTES: PFBA = perfluorobutanoic acid ppb = parts per billion ND = not detected above the method detection limit Levels of PFBA appear to be stable or declining slightly in many of the municipal and non-municipal community wells that have been regularly sampled by MDH since early As an example, Figure 6 is a graph of the concentration of PFBA in the 11 Cottage Grove municipal wells from January 2007 to September The reasons for a decline are unclear, but could reflect 1) an actual decline in the levels of PFBA in the Jordan aquifer; 2) movement of the contamination plume through increased pumping of community wells to meet demand; or 3) improvements in the accuracy of the analytical method over time. Continued data collection should help determine if the decline is real, and shed some light as to its causes. MDH has also sampled several dozen non-community public wells located at churches, businesses, parks, and other locations throughout southern Washington and northern Dakota Counties. Results from these wells showed either no or low levels of PFBA. 16

19 Private Well Sampling In June 2005, following detection of PFCs in monitoring wells at the 3M-Woodbury Disposal Site (Weston, 2007a), the MPCA and MDH collected water samples from 15 private wells near the site. These wells were selected as being representative of the Quaternary sand and gravel deposits above the bedrock and the three bedrock aquifers (St. Peter, Prairie du Chien, and Jordan) in use near the disposal site. At that time, PFOS and PFOA were the only PFCs for which analytical methods had been developed by the MDH Public Health Laboratory. Neither PFOA nor PFOS were detected. In late early 2007, the detection of PFBA in Woodbury, Cottage Grove, and several other city wells led to sampling of residential and non-community public wells (such as churches, businesses, etc.). Sampling of these wells indicated the area of PFBA contamination also included the communities of Grey Cloud Island Township, Denmark Township, the western edge of Afton, and the southernmost portion of Maplewood. The total area of PFBA contamination (including the areas affected by the Oakdale and Lake Elmo sites) encompasses over 100 square miles. Residents within this area (and in all of Washington County) rely entirely on groundwater as the source of their drinking water. Most residents are connected to city water, but it is estimated there over 4,000 private wells in these communities. Given the scope of the potentially affected area, a private well sampling program was developed to provide rapid information regarding how far and how deep the PFC contamination had spread and where the highest concentrations were located. The state s County Well Index (CWI) was used to identify wells with geologic information in recorded driller s logs. Wells drawing water from each of the drinking water aquifers used in the investigation area were selected to provide geographic coverage of all of the neighborhoods in the potentially affected communities. More intensive sampling (i.e. sampling a higher density of wells) was undertaken in the following areas: 1) closest to and downgradient of the disposal site, 2) where PFBA concentrations were highest, 3) where the bedrock geology is complicated by faults and/or bedrock valleys, and 4) where spatial trends in PFBA concentrations were unpredictable. Sampling proceeded in an iterative fashion with each round of sampling results informing decisions about the next round of samples. This allowed the MPCA and MDH to refine the sampling plan to identify and focus on areas of greatest potential health concern. By the end of 2008, water samples had been collected from over 900 residential and 56 business wells in the affected communities. A general summary of sampling results is provided in Table 2 (in Appendix 2). The most commonly detected contaminant in private and business wells in the investigation area is PFBA. PFPeA is also frequently detected, but is typically found only in wells with PFBA concentrations of 1 ppb or greater. Most of the wells sampled were completed in the Prairie du Chien, Jordan, and Franconia aquifers, or had no record to indicate the aquifer in which they were completed. Figures 7 10 show the distribution of PFBA in the four major drinking water aquifers (St. Peter, Prairie du Chien, Jordan, and Franconia). 17

20 Other PFCs have been detected at the 3M-Woodbury Disposal Site and in two isolated areas of Cottage Grove. The first area is located south and west of Highway 10, primarily in the Langdon and River Acres neighborhoods, where multiple PFCs have been detected at low concentrations in some private wells. The second area is the main Cottage Grove city well field, where trace levels of PFHxS, PFBS, PFPeA, and PFHxA have been detected in several community wells. Further information on these detections is provided below. PFC-Related Investigations at the 3M-Woodbury Disposal Site To better define residual PFC levels in soil and waste materials at the site and provide some clues as to the source(s) of PFCs in groundwater, in April M s consultant, Weston, installed a series of soil borings in the former Northeast Disposal Area (Weston, 2008a). Available historic information for the site suggested the presence of two trenches separated by soil mounds. A total of 14 soil borings were drilled using direct-push drilling technology, generally to a depth of ten feet. Selected borings within the trench features were advanced to the bedrock, approximately 20 feet deep. Soil samples were collected continuously to characterize the soil cover (1.5 to 6.5 feet) and backfill material (1.5 to 17 feet) thickness and depth, as well as other descriptive information. Soils were also screened for organic vapors and ph. Selected soil samples were collected based on visual appearance and sent to the 3M Environmental Laboratory for PFC analysis. Selected samples were also analyzed for VOCs. The soil boring locations and results for PFOS, PFOA, and PFBA in the Northeast Disposal Area are presented in Figure 11. PFC concentrations were generally higher in the backfill material in the former trench areas than in the mound areas. PFOA was detected in each of the soil samples collected in the former trench areas, at levels that range from 1,220 ppb to 26,100 ppb. Lower levels of PFBA were detected in 20 of 21 soil samples collected in the former Northeast Disposal Area. PFBA levels in the former trench areas ranged from 15 to 175 ppb. PFOS was detected in 11 of the 12 samples collected from backfill material in the former trenches. Detected concentrations ranged from 2,800 to 19,300 ppb. Other PFCs were infrequently detected; most notable was PFHxS in 11 soil samples at levels that ranged from 283 to 10,100 ppb. Petroleum related and chlorinated VOCs were also commonly detected in soil samples. In the fall of 2007, soil borings were installed to further assess the material remaining in the disposal trenches at the former Main Disposal Area and Municipal Fill Areas for PFCs. Eighteen direct-push borings were completed within the eight former Main Disposal Area trenches (A-H) and two former Municipal Fill Areas (I, J). With approval from the MPCA, soil samples from this area were analyzed for a smaller list of five PFCs (PFOA, PFOS, PFHxS, PFBA and PFBS). Two soil samples were collected and analyzed for the five PFCs from each soil boring, usually one sample from the bottom of the disposal trench and a second sample from approximately five feet below the bottom of the trench. The soils borings ranged in depth from eight to 28 feet. The soil boring locations and PFC results for these areas are shown in Figure

21 PFCs were detected at each of the soil boring locations within the former Main Disposal Area. PFC concentrations in the samples collected from beneath the fill/waste material were either non-detect or were less than that of the samples collected from the fill/waste material. The highest PFC concentration (PFOA at a concentration of 3,020,000 ppb) was detected at boring GPA04 at a depth of 16.5 feet. PFOS was detected at each of the 14 borings in the Main Disposal Area, at concentrations that ranged from 197 ppb to 17,600 ppb. PFBA was detected at lower concentrations compared to PFOA and PFOS, ranging from 1 to 225 ppb. Lower levels of PFCs were found in the soil samples collected from the four borings drilled in the former Municipal Fill Area. In 2008, the MPCA requested that 3M collect a water sample from a small pond on the site known as Gables Lake. This pond is located approximately 2,000 feet south of the former Main Disposal Area, as shown in Figure 3. A sample collected one foot below the surface of the lake contained ppb PFBA, ppb PFOA, and ppb PFOS (Weston, 2009). In , twenty additional monitoring wells were installed to provide additional information about PFC distribution at the site and to monitor for any movement of contaminants away from the site (Weston, 2007a). Sampling has shown that PFCs are present in multiple monitoring wells at the site, primarily downgradient of the waste (Table 3, Appendix 2). The highest levels have consistently been found in monitoring well MW-2, near the Northeast Disposal Area (Figure 3). PFC concentrations at the site have been stable over the limited sampling period, and generally low concentrations are detected in wells near the boundaries of the 3M property. However, only three of the monitoring wells completed in the Prairie du Chien (wells MW-S06PC, MW-4L and MW-5) actually intersect the high transmissivity zone (HTZ) identified by Tipping, et al. (2006), which 3M s consultant identified as likely carrying the majority of flow in the Prairie du Chien (Weston, 2008a). MW-S06PC is located upgradient of the waste disposal areas and wells MW-4L and MW-5 are located west and west-southwest of the disposal areas, respectively (Figure 3). As discussed later in this report, although the regional groundwater flow direction is to the south-southwest, the highest PFC concentrations in groundwater are located south of the site in the area of the buried bedrock valley. The absence of monitoring wells intercepting the HTZ south of the site in the area where highest PFBA concentrations have been detected, and to the southwest (i.e. downgradient) of the high PFBA concentrations in the bedrock valley, means it is possible that a critical pathway for PFC migration may be missed by the monitoring network. A groundwater remediation system is in operation at the 3M-Woodbury Disposal site. The system was originally installed to control migration of VOCs. The groundwater remediation system includes four gradient control/recovery wells. The system pumps an average of 4.6 million gallons of water per day from the wells. The water is discharged through a six mile long pipeline to the 3M-Cottage Grove facility where it is primarily used for non-contact cooling water prior to discharge to the Mississippi River under a permit issued by the MPCA. A hydraulic conductivity zone analysis was conducted by 19

22 Weston (2007b) which concluded the gradient control wells are fully containing the contamination on-site. This is consistent with previous evaluations of the gradient control system. However, possible gaps in the monitoring network, as described above, make it impossible to verify this. 3M proposed reducing the pumping rate at the disposal site, first by 25 percent and then, if no evidence is observed of contaminant migration from the site, by 50 percent (3M, 2010b). In their approval letter (MPCA, 2010a), the MPCA stated that groundwater data generated during the initial (25%) pumping rate reduction will be reviewed to determine what conditions, such as placement of additional monitoring wells that intercept the HTZ, might be necessary before any further pumping reductions might be allowed. To determine if potential leakage from the pipeline carrying the pumped-out water from the site could be contributing to groundwater contamination in South Washington County, the MPCA requested that 3M conduct a thorough evaluation of the integrity of the line (Weston, 2008a). This was done over a period of several weeks during April and May The evaluation was done using direct sensing technology wherever possible (i.e. it was not done by measuring water flow into and out of the pipeline). No leaks were detected in the conveyance pipeline. There were two pipeline segments, located in Cottage Grove Ravine Park, where the evaluation was difficult because the segments were too long and inaccessible. Evaluating shorter pipeline sections in this area was not feasible due to the difficult physical setting (steep elevations, wooded areas, asphalt surfaces, etc.) and/or the pipeline depth (over 10 feet deep in some areas). 3M indicated that this portion of the pipeline was more recently installed (in 2003) and that it was intact at that time. 3M has also indicated that there are pressure monitoring points where the four groundwater extraction wells enter the pipeline, and where the line ends at the 3M Cottage Grove facility (3M, 2008). 3M has stated that any significant leaks from the line would be quickly detected and reported, and that no such leaks have been reported recently. MPCA 3M Consent Order for PFC Disposal Sites At the MPCA April 24, 2007 Citizens Board meeting, the Board was asked to approve a series of enforcement actions under the state Superfund law to ensure 3M undertook response actions to address the PFC contamination from three known PFC disposal sites: the 3M-Cottage Grove facility, the 3M-Woodbury Disposal Site, and the 3M-Oakdale Disposal Site (MPCA, 2007c). The former Washington County Landfill was not included because under the MPCA Closed Landfill Program, the MPCA has assumed responsibility for the site. Instead of approving the enforcement actions, the Citizens Board directed MPCA staff to negotiate a Consent Order with 3M on PFC contamination in Minnesota (MPCA, 2007d). A Consent Order is a site cleanup agreement between the MPCA and a responsible party. The Board directed staff to address seven concerns with regards to the disposal sites and proposed actions in the Order, as follows: 20

23 1. A rigorous, robust cleanup plan for the disposal sites. 2. Recognition of the MPCA s jurisdiction. 3. Municipal and private drinking water supplies addressed. 4. Address future actions on PFBA. 5. Address additional studies on health and environmental effects. 6. Address cooperation from 3M on sharing research and information. 7. Preserve the MPCA s right to take action in the future. The MPCA and 3M negotiated the Order, and presented it to the MPCA Citizens Board for approval at its May 22, 2007 meeting. The Citizens Board unanimously approved the Consent Order with 3M. The consent order can be accessed on the MPCA web site at: (MPCA, 2007e): In the Consent Order, 3M agreed to contribute up to $8 million to remediate the former Washington County Landfill. 3M is also obligated under the Consent Order to provide alternate sources of drinking water in the case where PFC levels in a public or private well exceed MDH health-based exposure limits. Also included in the Consent Order is an agreement that the MPCA does not waive its right to pursue any natural-resource damage claims related to releases of PFCs from the sites. 3M provides regular updates to the MPCA and MDH on various activities under the Consent Order; the MPCA Board is updated on a quarterly basis by MPCA and MDH staff on 3M s progress under the Consent Order. Remedial Options for the 3M-Woodbury Disposal Site Based on data collected during previous investigations conducted at the site, and the PFC-related investigations described above, 3M has evaluated various response action alternatives for the site (Weston, 2008a). The alternatives evaluated by 3M and Weston, both sitewide and for specific contaminated media, include: Sitewide Alternative 1 No action. Sitewide Alternative 2 Institutional controls, access restriction and groundwater monitoring. Groundwater Alternative 1 Continued groundwater recovery with GAC treatment, as necessary, to meet appropriate discharge criteria. Soil Alternative 1 Excavation of the former Northeast Disposal Area trenches; disposal at an existing off-site landfill. Soil Alternative 2 Excavation of the former Northeast Disposal Area trenches; disposal at an existing off-site landfill; and 4 feet (minimum) cover over selected areas in the former Main Disposal Area. Soil Alternative 3 Excavation of the former Northeast Disposal Area trenches and selective removal of soil which exceeds Industrial SRVs from trenches in the former Main Disposal Area; disposal at an existing off-site landfill. Each of the response action alternatives was evaluated against the primary goal of protecting the public health and the environment. The proposed response actions also 21

24 were evaluated in light of the requirements agreed to by 3M in the Consent Order. Finally, the response action alternatives were evaluated using the following balancing criteria: 1) long-term effectiveness; 2) implementability; 3) short-term risks; and 4) total costs. A no action alternative is evaluated at every site. Based on these evaluations, 3M proposed the following recommended response action alternatives for the site: Institutional controls, access restriction, and groundwater monitoring (Sitewide Alternative SW-2), and Continued groundwater recovery with GAC treatment as necessary (Groundwater Alternative GW-1). 3M also stated that any of the three soil alternatives were acceptable, but left the final decision to the MPCA. The MPCA selected Soil Alternative 3, which included the most extensive soil and waste excavation, and documented their decision in a Minnesota Decision Document for the site dated December 22, After further analysis, MPCA determined that by slightly reducing the mass of PFCs removed from the site, the cleanup could be completed much sooner and at less cost to the environment in terms of fuel use, truck mileage, and landfill space. This modified Soil Alternative 3 is in fact the plan being implemented at the site by 3M. Additional details on the cleanup of the site, including various steps taken to prepare the site for cleanup can be found on the MPCA s web site at 3M began this phase of soil cleanup work at the site in the summer of Approximately 24,900 cubic yards of soil and waste were excavated from the main and northeast disposal areas and transported to the SKB Landfill in Rosemount, Minnesota. The soil and waste were placed in a dedicated cell constructed specifically to receive the soil and waste from the Woodbury and Oakdale sites, and waste that was buried at the 3M-Cottage Grove facility. An additional 2,750 cubic yards of excavated soil and waste from the main disposal area were transported for out-of-state disposal at a permitted hazardous waste facility due to the presence of other regulated contaminants. Site Visits MDH staff has conducted several visits to the 3M-Woodbury Disposal Site and its vicinity during the past three years to conduct private well searches, collect well water samples, and attend local government and public meetings. The 3M-Woodbury Disposal Site is partially fenced, and access from County Road 19 is limited by several locked gates. No Trespassing signs are also prominently placed along the fence and gates. However, MDH staff were shown by neighbors where the fencing has fallen into disrepair along the south border of the property; foot trails onto the property and information from nearby residents indicate at least some trespassing does occur. 3M reports that they have regular security patrols at and around the site. 3M allows some of the land to be used for agricultural purposes, and employee recreational activity clubs also use portions of the site, but these areas are not located near the former disposal sites. 22

25 Demographics, Land Use, and Natural Resources Nearly 150,000 people live in areas of Washington and Dakota Counties where measurable levels of PFBA have been detected in community water supplies or private wells. The estimated 2008 populations for the affected cities and townships are (Minnesota Department of Administration, 2009): Woodbury: 58,430 Cottage Grove: 34,017 St. Paul Park: 5,293 Newport: 3,542 Afton: 2,899 Denmark Township: 1,726 Grey Cloud Island Township: 362 Hastings: 22,488 South St. Paul: 20,250 These cities and townships represent a variety of land uses, from a typical suburban mix of compact residential areas, light commercial districts, and retail areas, to mainly rural residential and agricultural areas. The area has experienced significant population growth and development in the last ten to twenty years. In the larger cities, the majority of the population is served by community water supplies, but more rural areas rely on private wells for drinking water, and will for the foreseeable future. The area is home to numerous parks and recreational areas, including Afton State Park, St. Croix Bluffs and Cottage Grove Ravine Regional Parks, Point Douglas Park, and the Carpenter Nature Center. MDH has collected water samples from drinking water wells within the parks to look for the presence of PFCs. Low levels of PFBA were detected in two wells serving the Carpenter Nature Center (0.9 and 1.8 ppb), one well at Cottage Grove Ravine Regional Park (0.5 ppb), and the well serving Point Douglas Park (0.1 ppb). No PFCs were detected in wells at Afton State Park, or St. Croix Bluffs Regional Park. Both of these parks are on the eastern border of Washington County, along the St. Croix River. In August 2007 MDH issued a press release announcing revised fish consumption advice for several lakes in the Twin Cities metro area, including Ravine Lake, which is located within Cottage Grove Ravine Regional Park. The press release was issued due to the detection of PFOS in fish tissue samples collected by the MPCA from several lakes at levels high enough to warrant revised fish consumption advice for certain fish species. In the case of Ravine Lake, fish consumption advice was issued recommending no more than one meal per week of black crappie and largemouth bass. Additional data collected by the MPCA later in 2007 resulted in new fish consumption advice being issued for one other lake in south Washington County, Powers Lake in Woodbury, based on PFOS levels in fish. For specific guidance, please refer to MDH s Fish Consumption Advice 23

26 web site at The specific source of the PFOS detected in fish in these lakes is not clear. General Regional Issues This region of the eastern Twin Cities metropolitan area will likely continue to experience substantial population growth in the coming years, although development has slowed recently due to the economic downturn in Because continued growth may present a strain on area resources such as water supplies, the need for expansion of water supply systems has been evaluated by the cities and new community supply wells will be needed. The widespread PFC contamination in the aquifers typically used for municipal water supplies has complicated this process. Currently, Woodbury and Cottage Grove are in the process of siting or constructing new community wells to meet projected demand. Community Concerns MDH staff have had numerous contacts with citizens living in the affected areas of Washington, Dakota, and Ramsey Counties who have expressed concern about PFCs in their private well or the community water supply. Community meetings were held by MDH and MPCA in Hastings, Woodbury, Cottage Grove, St. Paul Park, and South St. Paul in February 2007, and again in February A total of approximately 400 people attended these meetings. MDH has also attended many other local meetings in the two cites, and responded to hundreds of phone calls and s. Some residents have expressed concern about the following: that cancer or other disease rates in the area seem higher than normal, the health implications for children who may have been exposed to contaminated water (both before and after birth), the health of domestic animals that may be drinking contaminated water, and the potential for uptake of PFCs by plants irrigated with contaminated water. Residents also had questions about multiple exposure pathways to PFCs, and the lack of health-based exposure limits for some PFCs in water. MDH has made every effort to address these health issues where possible, including an analysis of cancer rates that is described later in this report. MDH has produced multiple information sheets for area residents, regularly updated its web site on PFCs ( and created an distribution list (1,330 subscribers as of September 2009) to notify interested residents and local officials of new information. The cities (and Washington County) have also provided updates for local residents in their city newsletters, annual water quality reports, and web sites. There have also been numerous stories in state, Twin Cities, and local media. A draft version of this Public Health Assessment report was released for public comment on August 25, MDH received written comments from State Senator Katie Sieben, the MPCA, and 3M (Appendix 3). Sen. Sieben s comments primarily focused on the unknowns regarding past PFC exposure levels, possible long-term health effects, and the need for continued monitoring of water quality and public health in the affected communities (Sieben, 2010). The MPCA comments focused primarily on differences in interpretation regarding the adequacy of the monitoring well network at the 3M Woodbury Disposal Site and the source PFCs (other than PFBA) in the Langdon-River 24

27 Acres neighborhood in south Cottage Grove (MPCA, 2010b). These comments were addressed in the PFC-Related Investigations at the 3M-Woodbury Disposal Site and Evaluation of Impacts to Groundwater sections of this document. 3M s comments addressed a number of areas, but primarily focused on: differences in hydrogeologic interpretations, the adequacy of the monitoring well network, 3M s PFC waste disposal and reporting history, PFC toxicology and the potential for human health effects associated with PFC releases from the 3M-Woodbury Disposal Site, and the recommendation to extend city water to the most contaminated neighborhoods (3M, 2010a). These comments were addressed, as appropriate, throughout the document, but primarily in the PFC-Related Investigations at the 3M-Woodbury Disposal Site, Evaluation of Impacts to Groundwater, Exposure Through Private Wells, and Public Health Implications of PFC Exposure sections of this document. Evaluation of Environmental Fate and Exposure Pathways Introduction PFCs, primarily perfluorooctanoic acid (PFOA; C8F15O2H) and one of its salts, ammonium perfluorooctanoate (APFO; C8F15O2NH4), as well as lesser amounts of other PFCs such as perfluorooctanesulfonyl fluoride (POSF; C8F17SO2F) and perfluorobutanoic acid (PFBA, C4F7O2H) were manufactured by 3M at their Cottage Grove facility (formerly known as Chemolite) from the early 1950s until Production of the fourcarbon compound, perfluorobutanoic acid (PFBA) ceased in M currently produces perfluorobutane sulfonate (PFBS)-based products which are substitutes for the earlier eight-carbon PFCs. PFBS is also a four-carbon compound. In addition, 3M continues to use and/or produce one- to three-carbon perfluoroalkyl substances at the Cottage Grove facility (3M, 2010a). One of the byproducts of the production of POSF is perfluorooctane sulfonate (PFOS; C8F17SO3 - ), which can also be produced by the subsequent chemical or enzymatic hydrolysis of POSF. The chemical structures of PFOA, PFOS, and PFBA are shown in Figure 2. In 2000, 3M announced it was voluntarily phasing out production of all of its eightcarbon PFCs, including PFOS and products which could degrade or metabolize to PFOS. 3M ceased production of PFOA, PFOS and precursor materials by the end of In its reformulated stain repellent and other commercial products such as Scotchgard TM, 3M used a chemistry based on the four carbon sulfonic acid, PFBS, instead of the eight carbon PFOS (Brezinski 2003) and such production continues today. EPA has prohibited the production or import of PFOS and PFOS precursors, except for certain critical use exemptions where no alternatives were available and the use involves very low volumes and low exposure risk. There are still some commercial uses of PFOS in specialty products (primarily in the semi-conductor, metal plating, and aviation industries). 3M ceased production of PFBA in To the knowledge of MDH, there is currently no commercial production of PFBA in the U.S., but some PFBA is reportedly imported for commercial applications and for use in analytical laboratories, which may also use other four-carbon compounds that break down to PFBA in the environment. Certain 25

28 fluorochemicals which break down to PFBA in the environment have also been used in pesticides, although it is not clear whether this use continues today. Environmental Fate The carbon-fluorine bond is a high-energy bond, one of the strongest known among organic molecules. As a result, the chemical structures of the PFCs described above make them extremely resistant to natural breakdown, and they are persistent once released to the environment. Their structure also makes them excellent surfactants. The word surfactant is an acronym for 'surface active agent' - a molecule that lowers surface tension in a liquid. Surfactant molecules contain both a hydrophobic ( water-hating ) and hydrophilic ( water-loving ) component, making them semi-soluble in both organic and aqueous solvents. Surfactants are the active ingredients in soaps and detergents, where the hydrophobic component sticks to grease and dirt while the hydrophilic section sticks to water, helping to remove dirt from skin and hair and stains from fabric. These same properties can also be used to essentially help make materials resistant to water and stains, one of the primary markets for these chemicals. Information on the physical properties of PFCs that would make them potentially useful in industrial applications was published by 3M scientists in technical journals as far back as the early 1950s (Kauck and Diesslin, 1951; Reid et al., 1955). On the basis of its physical properties, PFOS is essentially non-volatile, and would not be expected to evaporate from water (OECD, 2002). In soil-water mixtures, PFOS has a strong tendency to remain in water due to its solubility (typically 80% remains in water and 20% in soil). PFOS does not easily adsorb to sediments, and is expected to be mobile in water at equilibrium (3M, 2003a). PFOA is slightly more volatile than PFOS, although it also has a very low volatility and vapor pressure (EPA, 2002). PFOA salts are very soluble and completely disassociate in water; in aqueous solution PFOA may loosely collect at the air/water interface and partition between them (3M, 2003b). In published studies and reports, PFOA has shown a high mobility in some soil types (EPA, 2002). In a study of the sorption potential for various PFCs in sediments, Higgins and Luthy (2006) found that the carbon chain length had a major effect on sorption potential the longer the chain the more likely adsorption would occur, and that perfluorosulfonates (i.e. PFOS) tended to bind more readily to sediment than perfluorocarboxylates (i.e. PFOA). Other environmental conditions that could affect adsorption include organic carbon content of the sediment, ph, and dissolved calcium. Other studies have shown generally similar results, and adsorption behavior in soils is likely to be very similar to that observed in sediments (Prevedouros et al., 2006). A review of the bioaccumulation potential of a variety of PFCs by Conder et al. (2008) found similar results, in that PFOS and longer chain perfluorocarboxylates (greater than eight carbons) had a greater potential to accumulate in living organisms. The vapor pressure and water solubility of PFBA are similar to PFOA (Kwan, 2001). PFBA is very soluble in water, and appears to travel easily with groundwater. A number of fluorinated compounds (fluorinated benzoates, not perfluorinated chemicals) are in fact used as tracers in groundwater flow studies due to their environmental persistence 26

29 and negligible adsorption to soil and aquifer materials (Flury and Wai, 2003; Shapiro, 2008). The study of sediment adsorption of selected PFCs by Higgins and Luthy (2006), which unfortunately did not include PFBA, nonetheless supports the notion that PFBA may be even more mobile than PFOA or PFOS in the environment because it is a perfluorocarboxylate with a short carbon chain length. Evaluation of Impacts on Groundwater The information obtained from investigation and remedial activities at the disposal sites, surface water sampling, and sampling of private, municipal, and non-community wells has been used to evaluate the magnitude, extent, and possible migration history of the PFC contamination in south Washington County. PFBA has been detected in all four of the major drinking water aquifers in the investigation area, with the most widespread contamination documented in the Prairie du Chien and Jordan aquifers (these are also the aquifers most widely used in this area and so have the most wells to be sampled). The extent of contamination in the St. Peter and overlying Quaternary sands and gravels is poorly understood, due to the few number of wells present in those aquifers. Contamination in the Franconia is generally low in concentration and appears to be localized near major bedrock faults that have brought the Franconia into contact with the Jordan (Figure 4), allowing PFCs in the Jordan to migrate into the Franconia. An area of contaminated groundwater is often referred to as a plume (like a plume of smoke). Typical contaminant plumes have their highest concentrations near the source area, decrease in concentration with distance from that source, and are roughly elliptical in shape with the axis of the plume roughly in line with the direction groundwater is flowing. In contrast, the PFBA plume in the investigation area is quite complex (see Figures 8 and 9). The highest concentrations of PFBA are detected south of the site and appear to coincide with the buried bedrock valley that underlies the western edge of the site and trends south through Cottage Grove Ravine Park to the Mississippi River (Figures 8 and 9). Although the regional groundwater flow direction in the area of the site is to the southwest, bedrock features, such as faults and buried valleys, and even smaller scale features such as solution cavities within the bedrock, may exert significant control over groundwater and contaminant migration on a local scale. Similarly, a patch of slightly higher PFBA concentrations near the border of Cottage Grove, St. Paul Park, and Newport (shown in yellow, just southeast of the intersection of Hwy 61 and I-494) appears to follow the outline of the bedrock valley in that area (see Figure 8). An arm of that valley appears to trend back toward the site, but an absence of wells in this area limits our ability to definitely trace the zone of higher PFBA concentrations back to the site. Another unusual area within the plume is the seemingly isolated area of PFBA present in the Jordan aquifer near the St. Croix River in the southeastern portion of the investigation area (Figure 9). This area is bounded by a series of major bedrock faults and the top of the Jordan east of this faulted zone is over 200 feet lower in elevation than the top of the 27

30 Jordan to the west of the zone. The Jordan on the east side of this heavily faulted zone is essentially at the same elevation as the Franconia aquifer on the west side. As shown in Figure 10, PFBA is present in the Franconia west of the faulted zone and at concentrations similar to those found in the Jordan east of the fault. In other words, the PFBA plume appears to be migrating from the Jordan into the Franconia across a fault near the ravine, traveling through the Franconia as the groundwater moves to the eastsoutheast, and then crosses another fault and back into the Jordan near the St. Croix River, as illustrated in Figure 4. PFBA has also dispersed south from the two 3M waste disposal sites in Lake Elmo and Oakdale (Figure 1; MDH, 2008a), further complicating our understanding of the PFBA distribution in the area south of I-94. Groundwater modeling (Barr, 2005a) and measured PFBA concentration trends downgradient of those two disposal sites suggest they may be the source of the PFBA detected in parts of Maplewood, north Woodbury, and Afton, and may also contribute some of the PFBA contamination in the other affected communities. There are also areas with unusual PFBA distribution patterns that, at present, cannot be attributed to bedrock structures or migration from the northern disposal sites. The most striking of these is the finger of elevated PFBA in the Prairie du Chien aquifer extending north of the 3M-Woodbury Disposal Site (Figure 8). Although it appears to follow the same northeast-southwest orientation of the faults in the area, no fault has been identified in this portion of the investigation area. The mechanism that created this finger of PFBA has not been determined. Although PFBA is the most widely detected PFC in Washington County, multiple PFCs were detected at the disposal site and the 3M Cottage Grove facility, and are also found in private wells in several isolated areas of Cottage Grove (Figure 13). The largest area is located south and west of Highway 61, primarily in the Langdon and River Acres neighborhoods, where non-pfba PFCs (PFOA, PFOS, PFHxS, PFBS, PFPeA, and PFHxA) have been detected in some private wells, generally at low concentrations (see table below). Although Figure 13 shows three distinct areas with multiple PFCs south of Highway 61, there are few wells between these areas so currently it is not possible to determine whether they are hydraulically connected or separate plumes. The second area is the main Cottage Grove city well field, where trace levels of PFHxS, PFBS, PFPeA, and PFHxA have been detected in several of the wells (Table 4, Appendix 2). A trace level of PFHxA (0.06 ppb) has also been detected in one well near Tower Road, but this result has not been confirmed. Maximum Concentrations of non-pfba PFCs in Langdon/River Acres Area Private Well Water PFOA PFOS PFPeA PFHxA PFBS PFHxS NOTES: All concentrations in ppb PFC = perfluorinated chemicals 28

31 The presence of multiple PFCs, other than PFBA and PFPeA, in these two areas is unusual because these compounds are not usually detected in wells between the disposal site and the two areas described (Figure 14), although the relatively lower density of wells in this area means the data are somewhat limited. MPCA considered whether the multiple PFCs detected in these areas may be related to fire-fighting activities. Many fire-fighting foams used to fight chemical fires contain PFCs. The Cottage Grove Fire Department originally reported to the MPCA that it used small amounts of such foam in their training activities, which occur near the main city well field (Delta, 2008). However, the department later stated that although they use PFC-bearing foams to fight fires, they do not use them for training purposes. Another possible link to use of fire-fighting chemicals in the areas south of Highway 61 was considered. In late 2002, PFC-bearing foams were used to extinguish a major industrial fire immediately south of Highway 61 and the foams reportedly discharged to a wetland area immediately southwest of the Langdon neighborhood and upgradient of the River Acres neighborhood. However, the MPCA analyzed environmental data collected near the site of the fire as well as from other fire-fighting foam sites, and has concluded that the fire was not a major contributor to groundwater contamination in the area. Furthermore, the MPCA has determined that the source of the PFC contamination in the area is the 3M Woodbury Disposal Site (MPCA, 2010b; see comment letter in Appendix 3). It is the MPCA s responsibility to determine contamination sources, with MDH advice (MDH/MPCA Memorandum of Agreement to Address Groundwater Contamination Situations, June 2010, revised November 2010). As noted elsewhere, public health is being protected by provision of whole-house Granulated Activated Carbon (GAC) filters to homes served by wells with PFC contaminant levels above HRLs. On-going monitoring of private wells continues to track PFC concentrations in each of the affected drinking water aquifers across the investigation area over time. As with the initial sampling effort, more wells are sampled in areas which have: higher PFC levels, more complex geology, and/or unpredictable trends in PFC concentrations. In areas where concentrations are lower and the distribution patterns are predictable, sentry wells are sampled regularly to provide representative results for each of the aquifers in use in that area. These wells act as early warning sentries for any unusual results that might warrant sampling of additional wells in the area. The sampling schedule, both in terms of frequency and number of wells, is revised regularly as more data is collected and the behavior of the PFC plume in the affected communities is better understood. The number of wells sampled and the sampling frequency in most areas has decreased over time because the PFC concentrations are low and stable throughout most of the affected areas and so do not warrant frequent monitoring. Sampling of the monitoring wells at the disposal site also indicate stable concentrations and appear to indicate that, as a result of the groundwater capture system in operation there, PFCs are not migrating off-site. However, as noted above, the absence of monitoring wells screened across the high transmissivity zone in the Prairie du Chien south of the site (i.e. the direction in which the highest PFBA concentrations have been 29

32 observed) and southwest (i.e. downgradient) of the bedrock valley, may represent a gap in the integrity of the monitoring network. In 2010, the MPCA approved a request for 3M to reduce the number of wells and the volume of water being pumped at the site, on the condition that additional monitoring occur to ensure the reduce pumping rates did not result in movement of contaminants from the site. MPCA also noted that additional monitoring wells may be required if monitoring indicates they are needed (MPCA, 2010a). 3M has yet to reduce pumping rates. The groundwater monitoring results indicate PFC concentrations in all of the aquifers are stable. This is consistent with findings in Lake Elmo and Oakdale (MDH, 2008a) and suggests that the size, shape, and concentrations of the PFC plumes in the individual aquifers may have reached a state of equilibrium, so that even though PFCs continue to migrate with the groundwater, their concentrations remain generally stable. However, groundwater systems are inherently dynamic and conditions may change over time, which is why sampling of private wells continues to track any changes that may occur. Based on our understanding of the way PFCs move in the groundwater environment and the high flow velocities known to exist in the investigation area, it is likely the PFCs from the disposal site migrated rapidly through the affected communities relatively soon after the wastes were disposed and what is present today are remnants of contaminants slowly washing out of the aquifers. This slow washing out of contaminants is sometimes referred to as secondary flow or matrix diffusion, and occurs because there are major (i.e. larger, faster) flow paths and minor (i.e. smaller, slower) flow paths within the aquifer (Figure 15). The majority of the contaminants flow quickly through the major flow paths in an initial pulse, rapidly establishing the contaminant plume, while contaminants that moved into the minor flow paths slowly release over time at more dilute concentrations. If this is what happened in the investigation area, earlier concentrations in the aquifers may have been higher than what is currently being detected. However, due to the high level of uncertainty involved in such calculations, MDH has not attempted to calculate how high those concentrations might have been or how long the higher concentrations may have lasted. The persistence of PFCs in the environment means that ultimately the PFCs in the groundwater in Washington County will discharge to the Mississippi and St. Croix Rivers. However, the low PFC concentrations in the groundwater (except at the 3M Cottage Grove facility) and the large volume of flow in the rivers will likely dilute this discharge to low concentrations. Samples of water from the Mississippi River were collected as part of the investigation of the waste disposal areas at the 3M Cottage Grove Plant (MDH, 2005; Weston, 2008c). While elevated concentrations of PFCs were detected in samples near and immediately downstream of the plant, no PFCs were detected in water samples collected upstream of the plant. Low levels of PFOS ( ppb) were detected in sediment samples collected upstream of the plant. Although PFOS is found in the groundwater at the 3M-Woodbury site, it is not present in the groundwater in most of the areas covered by this report with the exception of the trace levels detected in 23 wells in the anomalous area south of Hwy 61 and much higher concentrations in the groundwater at the 3M-Cottage Grove facility. The distribution of 30

33 PFOS in the groundwater and the proximity of the contaminated sediments to the 3M Cottage Grove facility suggest the source of the PFOS in the contaminated sediments is the facility via discharge of waste water and contaminated groundwater. Exposure through Private Wells PFCs can affect human health only if the chemicals move from the environment and come into contact with or accumulate in a person s body. The movement of PFCs (or other contaminants) from the environment into a person s body is called an exposure pathway. An environmental exposure pathway contains five parts: (1) a source of contamination, (2) contaminant transport through an environmental material (i.e., soil, air, water, or food), (3) a point of exposure, (4) a route of human exposure, and (5) a receptor population. An exposure pathway is considered complete if evidence exists that all five of these elements are or have been present in a community or a given situation. More simply stated an exposure pathway is considered complete when people are likely to be exposed to the chemical of concern. A pathway is considered a potential exposure pathway if at least one of the elements is missing but could be found at some point. An incomplete pathway is when at least one element is missing and will never be present. A completed environmental exposure pathway to PFCs from the disposal of PFCcontaining wastes in disposal sites in Washington County exists through the consumption of PFC contaminated drinking water. Samples have been collected from over 900 private wells and 56 business wells in Woodbury, Cottage Grove, and other communities in south Washington County (south of I-94). PFCs have been detected in 745 private and business wells. No wells, public or private, south of I-94 have been found to contain PFBA at concentrations above the Health Based Value (HBV) of 7 ppb for PFBA. The highest PFBA concentration detected was 5.5 ppb, but the majority of wells sampled had PFBA concentrations below 1 ppb. As of late 2010, 34 private well owners in Cottage Grove and Grey Cloud Island had received a drinking water well advisory from MDH due to the presence of PFCs. All of these wells are located in neighborhoods south of U.S. Highway 61, in the area of anomalous PFC detections, as discussed above. Nine of these private wells have PFOA at concentrations above the HRL of 0.3 ppb; one of which also has PFOS at concentrations above the HRL of 0.3 ppb. Sixteen of the wells have concentrations of PFCs that exceed a Hazard Index value of one based on multiple PFCs. The remaining ten wells have PFC levels that are below current health advisory levels. The advisories for these ten wells, where multiple PFCs are present, were issued in 2007 when the health risks of PFBA were poorly understood and a HBV had not yet been set for it. The drinking water well advisories have remained in effect due to uncertainties over groundwater flow. 31

34 Where drinking water well advisories have been issued by MDH, exposures have been reduced to acceptable levels by the provision of bottled water and/or GAC filters by the MPCA. It is also possible that the use of owner-installed filter systems may have reduced past exposure to PFCs in drinking water. During the course of the investigation, it was found that a number of private well owners who subsequently received a drinking water well advisory due to PFCs had previously installed reverse osmosis water filters to remove nitrate, a common groundwater contaminant in the area (Barr, 2005b; MDH, 2002). Although not related to the PFC contamination, the high nitrate levels generally occur in the same places as higher PFC concentrations as their movement in the groundwater is controlled by the same bedrock features and groundwater flow that control the movement of the PFCs (Barr, 2003). Reverse osmosis filters, if maintained properly, are also very effective at removing PFCs according to a study conducted by MDH in 2008 (MDH, 2008b). The MDH study also documented which types of point-ofuse carbon filters are effective at removing PFCs from drinking water. Using adsorption factors developed by 3M for a similar GAC system installed at their Cottage Grove plant, the predicted breakthrough time for each filter can be calculated based on the influent concentration and an assumed water use rate of 300 gallons per day. MDH and MPCA staff use a tracking system to monitor water use at each home, and have collected multiple samples to monitor system performance. At average water use, the filters are predicted to last, in some cases, for years before maintenance is needed. The MPCA has determined that the filters will be changed according to a predictable, conservative schedule in order to ensure they operate effectively. In 2008, MDH conducted a biomonitoring study of PFCs in the blood serum of Oakdale city water users and private well users in Lake Elmo and Cottage Grove, whose wells exceeded Minnesota drinking water standards (MDH, 2009). The study found 100 percent of the exposed individuals had PFOA, PFOS and PFHxS in their blood serum, the average concentrations of which exceeded the averages for the general US population. A 2010 follow-up biomonitoring study was conducted with the same individuals to determine if removal of PFCs from the city and private well water (as a result installing GAC filters) had any effect on their blood serum PFC levels. Average PFOA, PFOS, and PFHxS blood serum concentrations decreased by 21%, 26% and 13%, respectively, indicating that GAC treatment of the water had effectively reduced PFC exposures and body burdens for the users of the treated water (MDH, 2011). Even though GAC filters are very effective in removing organic contaminants such as PFCs, MDH does not consider them to be the best long-term solution in areas where alternate water supplies are available. If not properly maintained, GAC filters are a friendly environment for bacterial growth. As noted above, nitrate is commonly found in the groundwater in south Washington County. Nitrate in standing water that remains in a GAC filter over long periods of time (such as an extended vacation when the house is unoccupied) may be converted by bacteria to nitrite at potentially unsafe levels (MDH 2007d). As a result, GAC filters require regular maintenance, which the MPCA is providing, but this is not an ideal solution for numerous individual households. 32

35 The length of time local residents were exposed to PFCs through their drinking water is unknown. As discussed above, exposures could have started soon after PFCs wastes were placed in the disposal sites, given the mobility of PFCs in the environment. It is also possible that the levels in the groundwater were higher than currently detected, although MDH has not attempted to determine what the concentrations may have been in the past or how long those higher concentrations may have lasted, due to the high degree of uncertainty involved in such calculations. Continued routine monitoring of select private wells with levels of PFCs below the health based drinking water standards will ensure that, if levels of PFCs rise, future exposure to levels above health-based exposure limits will be brief. Exposure through Public Water Supplies The municipal and community wells in the affected area were sampled for PFCs by MDH on a monthly basis through 2007, and are now sampled on a quarterly basis, and the results of monitoring are reported to the city staff. While not required under the federal Safe Drinking Water Act, some cities report PFC results in their annual Consumer Confidence Report to their water customers. MDH will continue to monitor the wells, but to date very little change (other than perhaps a slight declining trend) has been observed in PFC levels in the municipal and community wells. No individual municipal or community well in the affected communities covered by this report have exceeded current MDH health-based exposure limits for PFCs. The city of Oakdale has several community wells and the city of Lake Elmo has one non-operational well which have exceeded the MDH drinking water standards. This is described in a previous MDH report (MDH, 2008a). Exposure through other Pathways The use of water contaminated with low levels of PFCs for bathing, showering, or other incidental uses is unlikely to contribute appreciably to overall exposure. Ingestion of the contaminated water is by far the predominant exposure pathway. Use of PFC contaminated water for canning or cooking purposes may also contribute to exposure, as reported by Emmett et al. (2006a) and Holzer et al. (2008). Irrigation of plants with PFC contaminated water may possibly lead to some uptake of PFCs by the plants, also contributing to overall exposure. MDH is currently examining the potential for exposure to PFCs by analyzing soil and produce samples collected at properties in Oakdale, Lake Elmo, and Cottage Grove that have or had a PFC-contaminated water supply (see So-called market basket surveys of food products occasionally show low levels of PFCs. In a study conducted in the United Kingdom, PFOS was found at low concentrations in potatoes, some canned vegetables, eggs, and in the sugars and preserves food groups, while PFOA was detected only in potatoes (UK Food Standards Agency, 2006). A similar study in Spain found low levels of PFOS in fish, dairy products, and meat, while PFOA was only detected in milk (Ericson et al., 2008). A recent study of food items in Canada also found low levels of PFOS and PFOA in some food products, 33

36 including beef, fish, and microwave popcorn (Tittlemier et al., 2007). It is less likely that PFBA would be taken up by plants, but data are not available. The consumption of fish from local lakes or rivers where PFOS has been detected in fish populations represents a completed exposure pathway, although the source of the PFOS may not be in all cases from land disposal of PFC-containing wastes. The specific sources of exposure to PFOS, PFOA, and other perfluorochemicals in the general population are unclear, but could include consumer products, environmental exposures, or other occupational exposures (Butenhoff et al., 2006). Both PFOS and PFOA have been detected in samples of household dust collected from vacuum cleaner bags in Japan (Moriwaki et al., 2003), Canada (Kubwabo et al., 2005), and the U.S. (Strynar and Lindstrom, 2008), indicating the indoor environment is one potential source of exposure. Low ppt levels of PFOS have also been detected in rainwater collected in Winnipeg, Canada (Loewen et al., 2005). It should be noted that since 2000, levels of PFOS and PFOA in blood serum have decreased (Olsen, et al., 2008). Small amounts of unbound fluorotelomer alcohols that can break down to PFOA (or other PFCs depending on their specific composition; also referred to as PFC precursors) have also been found in consumer and industrial products (Joyce et al., 2006). Release of telomer alcohols, and subsequent degradation in the environment or by organisms, could also be a source of human exposure to PFCs. Public Health Implications of PFC Exposure This section briefly summarizes information reviewed on the toxicity of PFCs to animals and humans for this report, and summarize the public health implications of exposure to PFCs through drinking water in affected communities in south Washington County, Minnesota. Note: ATSDR published a draft Toxicological Profile for Perfluoroalkyl Compounds for public review and comment in May 2009 (available at The Toxicological Profile summarizes the available scientific literature on the toxicology of PFCs, as does a summary report by Lau et al. (2007). Both of these references provide a more detailed summary of the scientific literature on PFCs than is possible or appropriate for this report. Summary of Toxicological Information PFOS is well absorbed orally, but is not absorbed well through inhalation or dermal contact (OECD, 2002). Half-lives of PFOS have been estimated at over 100 days in rats in a single-dose study, and 200 days in a sub-chronic dosing study in cynomolgus monkeys (OECD, 2002). Animal studies have shown that, in their pure form, PFOA and APFO (its ammonium salt) are easily absorbed through ingestion, inhalation, and dermal 34

37 contact (EPA 2002; Kennedy 1985; Kennedy et al., 1986; Kudo and Kawashima, 2003) although there may be differences between animals and humans and this pathway may not be relevant for environmental (i.e. lower concentration) exposures. The estimated half-life of PFOA in animals ranges from four hours in female rats and nine days in male rats to 20 days in male cynomolgus monkeys (Kudo and Kawashima, 2003; Butenhoff et al., 2004). The mean blood serum half-life of PFOA in humans was estimated to be 3.8 years in a published study of 26 retired 3M workers, and the mean serum half-life of PFOS was estimated at 5.4 years (Olsen et al., 2007a). The mean serum half-life of PFHxS has been reported as 8.5 years. This indicates that some PFCs are retained in the human body for a much longer period than in mice, rats, or monkeys, and that carbon chain length is not necessarily directly related to half-life in humans. PFCs are not metabolized, and are excreted in the urine and feces at different rates in various test animal species and humans. Exposure to high levels of PFOA, PFOS, and PFBA is acutely toxic in test animals (Kudo and Kawashima, 2003; OECD, 2002; Takagi et al., 1991). Chronic or sub-chronic exposure to lower doses of PFOA in rats typically results in reductions in body weight and weight gain, and in liver effects such as an increase in liver weight and alterations in lipid metabolism (Kudo and Kawashima, 2003). Immune system effects have also been reported in mice exposed to high doses of PFOA (DeWitt et al., 2008). The liver appears to be the primary target organ of PFOA toxicity in rats, although effects on the kidneys, pancreas, testes, and ovaries have also been observed (EPA, 2002). Exposure to PFOA (and other PFCs) in rats results in a process in the liver known as activation of the peroxisome proliferator activated receptor alpha (PPARα). This phenomenon is considered to be limited to rats and similar test animals, and is not observed in primates. Some of the adverse liver effects observed in rats such as an increase in liver weight are in part attributed to peroxisome proliferation. Adverse liver effects in primates are likely the result of a different mode of action. Chronic exposure to PFOS at high doses has been shown to result in liver toxicity and mortality, with a steep dose-response curve for mortality in rats and primates (OECD 2002). Indications of toxicity observed in 90-day rat studies include increases in liver enzymes and other adverse liver effects, gastrointestinal effects, blood abnormalities, weight loss, convulsions, and death. Immunotoxicity has also been reported in studies conducted in mice at relatively low doses (Peden-Adams et al., 2008). 3M has suggested that these effects have not been reproduced by other researchers, and may be related to liver toxicity (3M, 2010a). Some long-term animal studies suggest that exposure to PFOA could increase the risk of tumors of the liver, pancreas, and testes (Kudo and Kawashima, 2003; EPA, 2002). The mechanism of potential tumor formation is unclear, but evidence suggests that the tumors are the result of promotion (via oxidative stress, cell death, or hormone-mediated mechanisms) and not from direct damage to the genetic material within cells (genotoxicity). The tumors observed in rats may be a result of peroxisome proliferation, and may not be of relevance in humans (Kennedy et al., 2004). 35

38 Various reproductive studies of rats followed for two generations showed postnatal deaths and other developmental effects in offspring of female rats exposed to PFOS and APFO (EPA, 2002; OECD, 2002). These studies demonstrate that exposure to APFO/PFOA and PFOS in sufficient doses can result in adverse effects on the offspring of rats exposed while pregnant. PFBA has not been studied as extensively as PFOA or PFOS, and until 2008 MDH lacked necessary information to derive a HBV for it. Like other PFCs, PFBA has been demonstrated to cause peroxisome proliferation in the livers of rats exposed through their diet or by intraperitoneal injection (Ikeda et al., 1985; Takagi et al., 1991). The effects of treatment with PFBA were less severe than was observed with PFOA in these two studies. Similar effects have been seen in mouse studies (Permadi et al., 1992). In a similar study comparing the effects of PFOA and PFBA on rat livers, Just et al. (1989) found that the effects of treatment with PFBA were similar to that of PFOA for some parameters measured in the study. A key question MDH considered in the development of the 2008 HBV for PFBA was its half-life in animals and humans. Chang et al. (2008) summarized data from a study of the pharmacokinetics of PFBA in several animal species. The study showed that PFBA was eliminated quickly through urine in male and female rats, with a half-life of approximately 8 hours in male rats and less than two hours in female rats. The half-life in monkeys was less than two days. In study published in 2008, the mean half-life of PFBA in four male employees at the 3M-Cottage Grove plant and seven male and three female employees at the 3M-Cordova, Illinois plant was calculated to be 72 hours in males and 87 hours in females (Chang et al., 2008). A 28-day oral toxicity study of PFBA in rats (Lieder et al., 2007) showed that male rats exposed to PFBA had increased liver weights and decreased cholesterol, and other minor effects that went away once the exposure was stopped. In this study, some rats were also exposed separately to PFOA as a positive control. The main differences between male rats given PFBA and PFOA were that PFBA treated rats did not have lower body weights, but did have lower cholesterol. PFOA exposed rats did have a reduction in body weight, exhibited less physical activity and overall health, and had slight reductions in parameters related to red blood cells. The findings of a developmental study of PFBA in mice conducted at the EPA laboratory in North Carolina was also reviewed by MDH (Das et al., 2007). In the study, exposure to PFBA by pregnant mice did not appear to significantly affect maternal weight gain or fertility. Some developmental delays were observed in the offspring of the mice, and developmental effects were considered a co-critical effect along with liver, blood and thyroid effects in establishing the HBV for PFBA. No animal studies regarding exposure to multiple PFCs at the same time have been located in the scientific literature. 36

39 The current MDH HRLs for PFOS and PFOA are based on toxicological studies conducted on cynomolgus monkeys. In the case of PFOS, the key study (Thomford, 2002) was used by MDH to derive a toxicity value (known as a reference dose, or RfD) of milligrams PFOS per kilogram of body weight perday (mg/kg-d). The RfD included a human equivalent dose adjustment to account for the long half-life in humans (5.4 years), as well as a total uncertainty factor of 30 (a factor of 10 to account for variability in sensitivity between humans and a factor of 3 to account for uncertainty regarding sensitivity between laboratory animals and humans). The critical effects used to determine the RfD were a decrease in serum high-density lipoprotein (i.e., HDL) and changes in thyroid hormones. For PFOA, the key study (Butenhoff et al., 2002) was used to derive an RfD of mg/kg-d. The RfD for PFOA included a human equivalent dose adjustment to account for the long half-life in humans (3.8 years), as well as a total uncertainty factor of 30. The critical effect used to determine the RfD was an increase in relative liver weight. The 2008 HBV for PFBA is based on toxicological studies conducted on rats. Several different HBVs based on different exposure periods (short-term, sub-chronic, and chronic) were derived based on more recent MDH practices. The lowest value, which in the case of PFBA is the short-term value, became the final HBV for all three exposure periods. For this value, a short-term RfD of mg/kg-d was derived from the key study (Butenhoff, 2007), which included a dose metric adjustment of eight due to the much shorter mean half-life of PFBA in humans (3 days) versus rats (9.22 hours). The total uncertainty factor was 100 (to account for variability in sensitivity between humans, uncertainty regarding sensitivity between laboratory animals and humans, and database insufficiencies). Summary of Human Exposure Information PFCs, primarily PFOS and PFOA, have been detected in the blood of U.S. citizens in multiple studies (Olsen et al., 2003, 2004a, and 2004b). PFCs have also been shown to cross the placenta. In a study of fifteen pairs of maternal and cord blood samples in Japan, Inoue et al. (2004) detected PFOS in the cord blood samples at approximately onethird the concentration in maternal blood. PFOA was detected in maternal blood, but not in cord blood. A similar study of 11 paired maternal and cord blood samples collected in Germany showed PFOS in cord blood at approximately 60% of the maternal blood concentration (Midasch et al..,2007). This study did detect low levels of PFOA (median of 3.4 ppb) in cord blood samples, slightly above that found in the maternal blood samples. A larger study conducted in the city of Baltimore measured ten PFCs in the cord serum of 299 newborns (Apelberg et al., 2007a). PFOS and PFOA were detected in nearly all of the samples, at a geometric mean level of 4.9 and 1.6 ppb, respectively. Other PFCs were detected much less frequently, and at lower levels. In a follow-up study (Apelberg, 2007b), a small (sub-clinical) negative association between both PFOA and PFOS cord serum concentration and birth weight and size was observed. A similar study conducted in Denmark showed an inverse correlation between maternal serum PFOA levels and birth weight, but no statistical association with PFOS (Fei et al., 2007). These (and other) studies appear to offer inconsistent findings of a potential reduction in birth 37

40 weight associated with increased PFOA and PFOS levels in serum (Steenland et al., 2010). The most comprehensive data on PFC levels in the blood of the U.S. population has been produced by the Centers for Disease Control and Prevention s (CDC) National Health and Nutrition Examination Survey (NHANES) as reported by Calafat et al. (2007a and 2007b). Blood serum data (PFOS, PFOA, PFHxS) have been reported for several thousand people, age 12 and above, for the survey years , and , as shown in the table below. Geometric mean data for PFCs, U.S. population, in ppb Survey Year PFOS PFOA PFHxS NOTES: PFCs = perfluorinated chemicals ppb = parts per billion The data suggest that PFC levels in the blood serum of the general population are declining, perhaps due to a reduction in the use of PFCs in consumer products. Many other PFCs were included in the NHANES sample analysis, but data are not presented here because the PFCs were below detection limits, or only sporadically detected. PFBA was not included in the NHANES analyses. Other studies of serum levels in Red Cross adult blood donors have shown similar declines in PFC concentrations (Olsen et al., 2008). Information on PFC levels in Washington County residents exposed to PFCs through drinking water has been collected through a biomonitoring pilot program created and funded by the Minnesota Legislature in 2007 (MDH, 2009). For the pilot study, health scientists interviewed and obtained blood samples from 196 randomly selected adult participants in order to measure the levels of seven PFCs in their blood. One half of the participants homes were served by private wells in Lake Elmo and Cottage Grove and the other half were served by the Oakdale municipal water system. The private wells had to have at least trace levels (0.1 ppb or greater) of PFOA or PFOS for the residents to be eligible for the study. PFOS, PFOA, and PFHxS were detected in all 196 participants of the study. The geometric mean results for the 196 participants were as follows: Geometric mean data for PFCs, MDH Biomonitoring Pilot Study, in ppb Survey Year PFOS PFOA PFHxS NOTES: PFCs = perfluorinated chemicals ppb = parts per billion 38

41 PFBA was detected in 55 (28%) of the 196 serum samples collected from the project population (PFBA level of detection (LOD) was 0.1 ppb), with a maximum detected value of 8.5 ppb. PFBS was detected in 5 (3%) of the 196 serum samples collected from the population (PFBS LOD was 0.1 ppb). With so many of the samples measuring below the level of detection, an accurate geometric mean or other measure of central tendency for PFBS could not be calculated. PFPeA and PFHxA were not detected in any of the 196 serum samples collected. Overall, the pilot biomonitoring showed that the levels of three PFCs were higher in east metro residents than in the U.S. population as a whole. There was little difference between the Oakdale and Lake Elmo/Cottage Grove participants. Individual results were mailed to those participants who indicated they wished to receive them. Participants also received other helpful information about national findings for PFCs in people s blood, PFCs in general, and ways to reduce exposure to PFCs. MDH has initiated a follow-up biomonitoring study to determine if blood levels of PFCs have fallen, now that exposures through drinking water in these populations have been reduced or ended for the most part. The largest investigation of human exposure to PFOA is taking place in the Ohio-West Virginia area, and grew out of a court settlement of a class action lawsuit against the DuPont Corporation in This investigation is known as the C8 Health Project, and information on it can be found on the project s web site, The project has enrolled 69,030 people who may have been exposed to PFOA through drinking water. The participants have been tested for PFOA (and some other PFC) exposure through analysis of blood samples. The project will also involve ten separate studies to help determine whether PFOA exposure is associated with any observable human health effects. Eight of the studies will focus on diseases such as cancer, heart disease, stroke, diabetes, immune function, liver and hormone disorders, and birth outcomes. Two studies will look at exposure to PFOA and its half-life in the general population. The studies are estimated to be complete in several years, although some preliminary results have been posted on the study s web site. Details of the studies and results can be found on the C8 Science Panel web site at Recently, a summary of the epidemiological studies conducted to date was published by the C8 Health Project directors (Steenland et al., 2010). Associations have been observed between PFOA levels in blood and other parameters such as uric acid in adults, serum cholesterol levels, and delayed onset of puberty. Firm conclusions regarding cause and effect have not yet been drawn, however, and any associations must be interpreted with caution. The State of West Virginia examined cancer rates in three counties near the West Virginia DuPont PFOA plant (Colsher et al., 2005). The study found that some tumors that may be associated with PFOA exposure in animal studies were elevated in some parts of the study area, but that the reported cancers could not be directly related to PFOA exposure through drinking water. Also, other chemical exposures were known to exist in the area. 39

42 Discussion of the Public Health Implications of PFC Exposure Blood levels of PFCs observed in the east metro area are well below levels of departure in animals (23 parts per million (ppm) for PFOA, 35 ppm for PFOS) used to calculate MDH HRLs (MDH, 2007a and 2007b). The level of departure is the serum level in an animal at which critical adverse health effects are observed. Blood levels are also well below levels measured in 3M-Cottage Grove plant workers (PFOA, geometric mean 850 ppb; PFOS, geometric mean 440 ppb; 3M, 2003c). Past studies of 3M workers have not observed reproducible or consistent health effects (i.e. Alexander et al., 2003); a more recent study by Lundin et al (2009) did suggest positive associations between PFOA exposure and prostate cancer, cerebrovascular disease, and diabetes in some 3M-Cottage Grove workers. MDH is closely following the ongoing 3M workforce studies, as well as the West Virginia study, which will provide more definitive information about the health implications of PFC exposure in the east metro area. On January 8, 2009, the U.S. EPA s Office of Water issued Provisional Health Advisories for PFOS and PFOA of 0.2 and 0.4 ppb, respectively (EPA, 2009). This action was taken in response to a situation in Alabama where it was found that sludge from a wastewater treatment plant that received PFC contaminated industrial wastewater had been land-applied. The sludge is believed to be responsible for low levels of PFOA found in nearby community water systems. The 2009 EPA Provisional Health Advisory values are very close to MDH s HRLs for PFOS and PFOA, but were calculated in a slightly different way. MDH has determined that if the EPA values were applied in situations where drinking water is contaminated with PFOS or PFOA, no additional well advisories or other health-protection actions would be necessary. MDH s health-based exposure limits are protective for all segments of the population, including vulnerable sub-populations. Nevertheless, those who may be especially concerned with their continued exposure to low levels of PFCs through drinking water (even at levels below MDH HRLs or HBVs), such as pregnant women or parents with infants, can take additional steps to reduce exposure by using bottled water for drinking, cooking, or making formula, or by using point of use filters to treat water used for these purposes. MDH recently completed a study of the effectiveness of point of use water treatment devices for PFCs which demonstrated that reverse-osmosis and activated carbon filters work well under both laboratory and real-world conditions (MDH, 2008b). Health Outcome Data Review On June 7, 2007 the Minnesota Cancer Surveillance System (MCSS), located within the Chronic Disease and Environmental Epidemiology Section of MDH issued a report presenting detailed profiles of cancer rates among residents of Dakota and Washington Counties (MDH, 2007c). Using MCSS data for the 15-year period , countywide cancer rates for all cancers combined and for each of about 25 of the most frequent types of cancer, including liver and thyroid cancer were examined. In addition, analyses were also conducted to examine incidence rates for 16 selected cancers for specific communities, by zip code, within each county. For that analysis, data from the years 40

43 were used, largely due to population growth in some communities and limitations on community census data. The report (which can be accessed at the MDH web site, found that overall cancer rates in Washington and Dakota counties are very similar to the rest of the state, or slightly lower. In addition, the rates and types of cancers that occurred within specific communities in the two counties were generally similar with other communities in the Twin Cities metropolitan area. Analyses of community cancer rates are rarely useful for evaluating potential cancer risks from low levels of environmental pollutants. Nevertheless, such data can be helpful in addressing public concerns over cancer rates in a county or a community. The reader is referred to the full report for a more detailed description of the benefits and limitations of the analysis. Child Health Considerations MDH recognizes that the unique vulnerabilities of infants and children are of special concern to communities faced with contamination of their water, soil, air, or food. Children are at a greater risk than adults are from certain kinds of exposures to environmental contaminants at waste disposal sites. They are more likely to be exposed because they often play outdoors and bring food into contaminated areas. Children are smaller than adults and so receive higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk-identification and risk-management decisions, housing decisions, and for access to medical care. Many children have been exposed to low levels of PFCs in contaminated drinking water in the affected communities described in this report. MDH health-based exposure limits are calculated with protection of children s health in mind. As stated previously, those who may be especially concerned with children s exposure to low levels of PFCs through drinking water, such as pregnant women or parents with infants, can take additional steps to reduce exposure by using bottled water for drinking, cooking, or making formula, or by using point of use filters to treat water used for these purposes. Conclusions PFC-containing wastes were disposed of by 3M in land disposal sites in Oakdale, Lake Elmo, Woodbury, and Cottage Grove, Minnesota. PFCs were released to groundwater from these sites, possibly shortly after the disposal occurred, resulting in contamination of nearby drinking water wells. The levels of PFCs in drinking water in the past are unknown and in the past exposure could have occurred through drinking water, possible air emissions during the handling, disposal, or burning of waste or direct contact with the 41

44 waste. A pilot biomonitoring study conducted in Oakdale, Lake Elmo, and Cottage Grove indicated levels of PFCs in resident s blood that are above national averages. While available evidence suggests that these PFC levels are unlikely to cause adverse health effects, there is no information available regarding PFC levels in resident s blood or in drinking water in the past. MDH cannot conclude whether drinking PFCs in water, breathing them in the air, or coming into direct contact with PFC-containing wastes in the past harmed people s health. Currently, PFCs have been detected in public and private wells across a wide area of south Washington County, and in parts of northern Dakota County and southeastern Ramsey County. In the areas covered by this report, the PFC concentrations are below levels of public health concern in all of the public wells and the vast majority of private wells. Exposure to PFCs at levels above health concern in 24 private wells in south Cottage Grove is currently being addressed by the use of bottled water or whole-house activated carbon filters. Biomonitoring studies indicate these measures have resulted in decreased average blood serum levels of PFOS, PFOA, and PFHxS for these water users. However, such filters require continued monitoring and maintenance to ensure they function properly. For those reasons, filter systems are not considered by MDH to be the best, long-term solution if other sources of water are available. MDH concludes that currently, the levels of PFCs found in drinking water from public or private wells in the area covered by this report are not expected to harm people s health; new data will be evaluated as it becomes available. Remediation actions to address PFCs at the waste disposal sites are underway by 3M and the MPCA. Recommendations 1. 3M should continue to follow the requirements of the Consent Order to implement the selected remediation options for soil and groundwater at the 3M Woodbury Disposal Site. 2. Although remedial actions at the site appear to have eliminated surface soil as an exposure pathway, as a precaution people should avoid trespassing on the 3M Woodbury Disposal Site and 3M should improve the fencing of the site, particularly along the south boundary, to prevent trespassing. 3. Extension of the Cottage Grove municipal water supply to serve areas where private wells contain levels of PFCs in excess of MDH HRLs or HBVs should be considered. 4. Monitoring of selected private wells in the affected area should continue under agreed upon sampling plans to track changes in the plume and monitor for changes in concentration in individual wells. If the plume remains stable, the frequency and number of wells monitored may be reduced while still providing assurance that public health is protected. 5. MPCA should continue to monitor and maintain whole-house GAC filter systems (or provide bottled water) in homes where the well water exceeds Minnesota drinking water standards. 6. MDH will continue to work with the City of Oakdale and 3M to ensure proper treatment of city wells that exceed Minnesota drinking water standards. 42

45 7. As part of the proposed reduction in groundwater pumping at the site, MPCA should evaluate the monitoring data to determine whether the monitoring well network at the 3M-Woodbury Disposal Site provides adequate information regarding water quality in the high transmissivity zone of the Prairie du Chien aquifer. Public Health Action Plan The MDH Public Health Action Plan for the site includes the following: 1) distribution of this public health assessment (and/or an information sheet summarizing the information contained in this public health assessment) to area residents; 2) continued consultation with the MPCA, 3M, Washington County, and the affected communities on implementing investigation and response-action activities and the recommendations provided in the Recommendations section of this document; 3) continued outreach to private-well owners; 4) continued monitoring of public water supplies; 5) organization and participation in public meetings and meetings with local government officials as needed, 6) evaluation of other potential pathways for environmental exposure to PFCs, and additional biomonitoring studies to evaluate PFC levels in area residents exposed to PFOA and PFOS in drinking water. 43

46 References 3M, 2003a. Environmental and Health Assessment of Perfluorooctane Sulfonate Acid and its Salts. 3M Company, St. Paul, Minnesota. August 20, M, 2003b. Letter from Michael A. Santoro, 3M, and George H. Millet, 3M, to the U.S. EPA Office of Pollution Prevention and Toxics. August 1, M, 2003c. Assessment of Lipid, Hepatic, and Thyroid Function in Relation to an Occupational Biologic Limit Value for Perfluorooctanoate. Medical Department, 3M Company, St. Paul, Minnesota June 9, M, Letter from Katie Winogrodzki, 3M, to Gerald Stahnke, MPCA. September 19, M, 2010a. Comments of 3M Company on Minnesota Department of Health s Draft Public Health Assessment on Perfluorochemicals in Southern Washington County, Northern Dakota County, and Southeast Ramsey County, Minnesota. October 12, M, 2010b. 3M Woodbury Site: Request to Reduce Barrier Well Pumping Rates. Letter to Mr. Douglas Wetzstein, MPCA, dated March 16, 2010 from Ms. Katie Winogrodzki, 3M. Alexander, B.H., Olsen, G.W., Burris, J.M., Mandel, J.H., and Mandel, J.S. Mortality of employees of a perfluorooctanesulphonyl fluoride manufacturing facility. Occupational and Environmental Medicine 60: Alexander, C., Fractured sandstone karst aquifers, the St. Peter, Jordan and Hinckley Formations: Examples for Askov, Woodbury, Rochester and Elsewhere. Presented at the Minnesota Groundwater Association spring conference, April 19, Apelberg, B.J., Goldman, L.R., Calafat, A.M., Herbstman, J.B., Kuklenyik, Z., Heidler, J., Needham, L.L., Halden, R.U., and Witter, F.R., 2007a. Determinants of fetal exposure to polyfluoroalkyl compounds in Baltimore, Maryland. Environmental Science and Technology 41: Apelberg, B.J., Witter, F.R., Herbstman, J.B., Calafat, A.M., Halden, R.U., Needham, L.L., and Goldman, L.R., 2007b. Cord serum concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in relation to weight and size at birth. Environmental Health Perspectives 115: ATSDR, Draft Toxicological Profile for Perfluoroalkyl Acids. Agency for Toxic Substances and Disease Registry, Atlanta GA. May Barr, Cottage Grove Area Nitrate Study Report. Prepared by Barr Engineering for Washington County. October

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51 Loewen, M., Halldorson, T., Wang, F., and Tomy, G., Fluorotelomer carboxylic acids and PFOS in rainwater from an urban center in Canada. Environmental Science and Technology 39: Lundin, J.I., Alexander, B.H., Olsen, G.W., and Church, T. R., Ammonium perfluorooctanoate production and occupational mortality. Epidemiology 20: MDH, Nitrate exposure and infant risk study (NEXIR). Accessed online at MDH, Health Consultation on Perfluorochemical Releases at the 3M Cottage Grove Facility. Minnesota Department of Health, St. Paul, Minnesota, February 18, MDH, 2007a. Health Based Values for Perfluorooctanoic Acid. Memorandum from Helen Goeden, Health Risk Assessment Unit to John Stine, Environmental Health Division Director. Minnesota Department of Health, St. Paul, Minnesota, February 26, MDH, 2007b. Health Based Values for Perfluorooctane Sulfonate. Memorandum from Helen Goeden, Health Risk Assessment Unit to John Stine, Environmental Health Division Director. Minnesota Department of Health, St. Paul, Minnesota, February 26, MDH, 2007c. Cancer Incidence in Dakota and Washington Counties. MCSS Epidemiology Report 2007:1. Minnesota Cancer Surveillance System, Chronic Disease and Environmental Epidemiology Section, Minnesota Department of Health, St. Paul, Minnesota. June 7, MDH, 2007d. Health Consultation on Nitrite Generation in a Granular Activated Carbon Filter Baytown Township Groundwater Contamination Site, Washington County, Minnesota, EPA Facility ID: MND Minnesota Department of Health, St. Paul, Minnesota, November 9, MDH, 2008a. Public Health Assessment on Perfluorochemical Contamination in Lake Elmo and Oakdale, Washington County, Minnesota. Minnesota Department of Health, St. Paul, Minnesota, August 29, MDH, 2008b. Performance Evaluation, Removal of Perfluorochemicals (PFCs) with Point-of-Use (POU) Water Treatment Devices. Minnesota Department of Health, St. Paul, Minnesota, May 1, MDH, East Metro Perfluorochemical Biomonitoring Pilot Project Report. Minnesota Department of Health, St. Paul, Minnesota, July 21, Online at: pdf 49

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53 MPCA, 2010b. MPCA Comments on MDH Draft Public Health Assessment 3M Woodbury Disposal Site. December 6, OECD, Hazard Assessment of Perfluorooctane Sulfonate (PFOS) and its Salts. Organization for Economic Cooperation and Development. November 21, Ohmori, K., Kudo, N., Katayama, K., and Kawashima, Y., Comparison of the toxicokinetics between perfluorocarboxylic acids with different carbon chain length. Toxicology 84: Olsen, G.W., Church, T.R., Miller, J.P., Burris, J.M., Hansen, K.J., Lundberg, J.K., Armitage, J.B., Herron, R.M., Medhdizadehkashi, Z., Nobiletti, J.B., O Neill, E.M., Mandel, J.H., and Zobel, L.R., Perfluorooctanesulfonate and other fluorochemicals in the serum of American Red Cross adult blood donors. Environmental Health Perspectives 111: Olsen, G.W., Church, T.R., Hansen, K.J., Burris, J.M., Butenhoff, J.L., Mandel, J.H., and Zobel, L.R., 2004a. Quantitative evaluation of perfluorooctanesulfonate (PFOS) and other fluorochemicals in the serum of children. Journal of Children s Health 2: Olsen, G.W., Church, T.R., Larson, E.B., van Belle, G., Lundberg, J.K., Hansen, K.J., Burris, J.M., Mandel, J.H., and Zobel, L.R., 2004b. Serum concentrations of perfluorooctanesulfonate and other fluorochemicals in an elderly population from Seattle, Washington. Chemosphere 54: Olsen, G.W., Burris, J.M., Ehresman, D.J., Froehlich, J.W., Seacat, A.M., Butenhoff, J.L., and Zobel, L.R., 2007a. Half-life of serum elimination of perfluorooctanesulfonate, perfluorohexanesulfonate, and perfluorooctanoate in retired fluorochemical production workers. Environmental Health Perspectives 115: Olsen, G.W., Mair, D.C., Reagan, W.K., Ellefson, M.E., Ehresman, D.J., Butenhoff, J.L., and Zobel, L., 2007b. Preliminary evidence of a decline in perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) concentrations in American Red Cross blood donors. Chemosphere 68: Olsen, G.W., and Zobel, L.R., Assessment of lipid, hepatic, and thyroid parameters with serum perfluorooctanoate (PFOA) concentrations in fluorochemical production workers. International Archives of Occupational and Environmental Health 81: Olsen, G.W., Mair, D.C., Church, T.R., Ellefson, M.E., Reagen, W.K., Boyd, T.M., Herron, R.M., Medhdizadehkashi, Z., Nobiletti, J.B., Rios, J.A., Butenhoff, J.L., and Zobel, L., Decline in perfluorooctanesulfonate (PFOS) and other perfluoroalkyl chemicals in American Red Cross adult blood donors, Environmental Science and Technology 42:

54 Peden-Adams, M.M., Keller, J.M., EuDaly, J.G., Berger, J., Gilkeson, G.S., and Keil, D.E., Suppression of humoral immunity in mice following exposure to perfluorooctane sulfonate (PFOS). Toxicological Sciences, advance published March 20, Permadi, H., Lundgren, B., Andersson, K., and DePierre, J.W., Effects of perfluoro fatty acids on xenobiotic-metabolizing enzymes, enzymes which detoxify reactive forms of oxygen and lipid peroxidation in mouse liver. Biochemical Pharmacology 44: Prevedouros, K., Cousins, I.T., Buck, R.C., and Korzeniowski, S.H., Sources, fate and transport of perfluorocarboxylates. Environmental Science and Technology 40: Reid, T.S., Codding, D.W., and Bovey, F.A., Vinyl esters of perfluoro acids. Journal of Polymer Science 18: Runkel, A.C., Tipping, R.G., Alexander, E.C., Jr., Green, J.A., Mossler, J.H., and Alexander, S.C., 2003, Hydrogeology of the Paleozoic bedrock in southeastern Minnesota: Minnesota Geological Survey Report of Investigations 61, 105 p., 2 pls. Runkel, A.C., Mossler. J.H., and Tipping, R.G., The Lake Elmo downhole logging project: hydrostratigraphic characterization of fractured bedrock at a perfluorochemical contamination site. Minnesota Geological Survey, St. Paul, Minnesota. November 1, Shapiro, A.M., Groundwater Flow and Chemical Transport in Fractured Rocks; USGS webinar, November 18, Sieben, K., Letter from State Senator Katie Sieben to the Site Assessment and Consultation Unit, Minnesota Department of Health. September 29, So, M.K., Tamashita, N., Taniyasu, S., Jiang, Q., Giesy, J.P., Chen, K., and Lam, P.K.S., Health risks in infants associated with exposure to perfluorinated compounds in human breast milk from Zhoushan, China. Environmental Science and Technology 40: Steenland, K., Fletcher, T., and Savitz, D.A., Epidemiologic evidence on the health effects of perfluorooctanoic acid (PFOA). Environmental Health Perspectives 118: Strynar, M.J. and Lindstrom, A.B., Perfluorinated compounds in house dust from Ohio and North Carolina, USA. Environmental Science and Technology 42:

55 STS, Surface Water Quality Criterion for Perfluorooctanoic Acid. Prepared by STS Consultants, Inc. for the Minnesota Pollution Control Agency. August Accessed online at: Takagi, A., Sai, K., Umemura, T., Hasegawa, R., and Kurokawa, Y., Short-term exposure to the peroxisome proliferators, perfluorooctanoic acid and perfluorodecanoic acid, causes significant increase of 8-hydroxydeoxyguanosine in liver DNA of rats. Cancer Letters 57: Tao, L., Kannan, K., Wong, C.M., Arcaro, K.F., and Butenhoff, J.L., Perfluorinated compounds in human milk from Massachusetts, U.S.A. Environmental Science and Technology 42: Thomford, P., 2002 Final Report: 104 Week Dietary Chronic Toxicity and Carcinogenicity Study with Perfluorooctane Sulfonic Acid Potassium Salt (PFOS: T 6295) in Rats. (Abstract only). Tipping, RG., Runkel, A.C., Alexander, E.C., Jr., Alexander, S.C., and Green, J.A. (2006) Evidence for hydraulic heterogeneity and anisotropy in the mostly carbonate Prairie du Chien Group, southeastern Minnesota, USA. Sedimentary Geology, 184: Tittlemier, S.A., Pepper, K., Seymour, C., Moisey, J., Bronson, R., Cao, X.L., and Dabeka, R.W., Dietary exposure of Canadians to perfluorinated carboxylates and perfluorooctane sulfonate via consumption of meat, fish, fast foods, and food items prepared in their packaging. Journal of Agricultural and Food Chemistry 55: UK Food Standards Agency, Flourinated chemicals: UK dietary intakes. Food Standards Agency, Chemical Safety Division. London, United Kingdom, November Weston, Fluorochemical (FC) Site Related Environmental Assessment Program, 3M Cottage Grove, Minnesota Facility. Weston Solutions, Inc., West Chester, Pennsylvania, July Westo,n 2007a. Fluorochemical (FC) Assessment Work Plan for the 3M Woodbury Site. Weston Solutions, Inc., West Chester, Pennsylvania, February Weston, 2007b. Hydraulic Evaluation of the Barrier Well Recovery System Former 3M Woodbury Disposal Site, Woodbury, MN. Weston Solutions, Inc., West Chester, Pennsylvania, September, Weston, 2008a. Remedial Investigation / Feasibility Study, 3M Woodbury Disposal Site. Weston Solutions, Inc., West Chester, Pennsylvania, February Weston, 2008b. Addendum 2 to the Feasibility Study for the Woodbury Site. Weston Solutions, Inc., West Chester, Pennsylvania, July

56 Weston, 2008c. Feasibility Study Cottage Grove Site. Weston Solutions, Inc., West Chester, Pennsylvania, March Weston, Gables Lake Surface Water Sampling Report, 3M Woodbury, MN Site. Weston Solutions, Inc., West Chester, Pennsylvania, July

57 REPORT PREPARATION This Public Health Assessment was prepared by the Minnesota Department of Health under a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with the approved agency methods, policies, procedures existing at the date of publication. Editorial review was completed by the cooperative agreement partner. ATSDR has reviewed this document and concurs with its findings based on the information presented. Authors James Kelly, M.S. Supervisor Indoor Air Unit Minnesota Department of Health Telephone: (651) james.kelly@state.mn.us Virginia Yingling, M.S. Hydrogeologist Site Assessment and Consultation Unit Minnesota Department of Health Telephone: (651) virginia.yingling@state.mn.us Technical Project Officer Trent LeCoultre, MSEH Cooperative Agreement and Program Evaluation Branch Division of Health Assessment and Consultation ATSDR 55

58 Glossary Acute Occurring over a short time [compare with chronic]. Acute exposure Contact with a substance that occurs once or for only a short time (up to 14 days) [compare with intermediate duration exposure and chronic exposure]. Adverse health effect A change in body function or cell structure that might lead to disease or health problems. Analyte A substance measured in the laboratory. A chemical for which a sample (such as water, air, or blood) is tested in a laboratory. For example, if the analyte is mercury, the laboratory test will determine the amount of mercury in the sample. Aquifer A geologic unit (sediments, rock) in which the pore spaces are fully saturated with groundwater and that can yield water in usable quantities for springs or wells. Bedrock valley A valley eroded into the bedrock by the action of streams, glaciers, wind, etc. If the valley is subsequently filled with sediment (sand, gravel, silt, or clay), it is referred to as a buried valley or buried bedrock valley. Biomonitoring Measuring chemical substances in biologic materials (such as blood, hair, urine, or breath) to determine whether exposure has occurred. A blood test for lead is an example of biologic monitoring. Biota Plants and animals in an environment. Some of these plants and animals might be sources of food, clothing, or medicines for people. Buried valley A bedrock valley that has been filled with sediment. See bedrock valley. Cancer Any one of a group of diseases that occur when cells in the body become abnormal and grow or multiply out of control. Cancer risk A theoretical risk for getting cancer if exposed to a substance every day for 70 years (a lifetime exposure). The true risk might be lower. 56

59 CERCLA [see Comprehensive Environmental Response, Compensation, and Liability Act of 1980]. Chronic Occurring over a long time [compare with acute]. Chronic exposure Contact with a substance that occurs over a long time (more than 1 year) [compare with acute exposure and intermediate duration exposure]. Completed exposure pathway [see exposure pathway]. Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) CERCLA, also known as Superfund, is the federal law that concerns the removal or cleanup of hazardous substances in the environment and at hazardous waste sites. ATSDR, which was created by CERCLA, is responsible for assessing health issues and supporting public health activities related to hazardous waste sites or other environmental releases of hazardous substances. This law was later amended by the Superfund Amendments and Reauthorization Act (SARA). Concentration The amount of a substance present in a certain amount of soil, water, air, food, blood, hair, urine, breath, or any other media. Contaminant A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful (adverse) health effects. Dermal Referring to the skin. For example, dermal absorption means passing through the skin. Dermal contact Contact with (touching) the skin [see route of exposure]. Detection limit The lowest concentration of a chemical that can reliably be distinguished from a zero concentration. Dose (for chemicals that are not radioactive) The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in 57

60 the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs. Dose-response relationship The relationship between the amount of exposure [dose] to a substance and the resulting changes in body function or health (response). Downgradient A location downstream relative to groundwater flow directions, or the direction to which groundwater is flowing. Environmental media Soil, water, air, biota (plants and animals), or any other parts of the environment that can contain contaminants. Environmental media and transport mechanism Environmental media include water, air, soil, and biota (plants and animals). Transport mechanisms move contaminants from the source to points where human exposure can occur. The environmental media and transport mechanism is the second part of an exposure pathway. EPA United States Environmental Protection Agency. Epidemiology The study of the distribution and determinants of disease or health status in a population; the study of the occurrence and causes of health effects in humans. Exposure Contact with a substance by swallowing, breathing, or touching the skin or eyes. Exposure may be short-term [acute], of intermediate duration, or long-term [chronic]. Exposure investigation The collection and analysis of site-specific information and biologic tests (when appropriate) to determine whether people have been exposed to chemical substances. Exposure pathway The route a substance takes from its source (where it began) to its endpoint (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has five parts: a source of contamination (such as an abandoned business); an environmental media and transport mechanism (such as movement through groundwater); a point of exposure (such as a private well); a route of exposure (eating, drinking, breathing, or touching), and a receptor population (people potentially or actually exposed). When all five parts are present, the exposure pathway is termed a completed exposure pathway. 58

61 Fault In geology, a fault is a planar rock feature which shows evidence of relative movement. Feasibility study A study to determine the best way to clean up environmental contamination. A number of factors are considered, including health risk, costs, and what methods will work well. Groundwater Water beneath the earth's surface in the spaces between soil particles and between rock surfaces [compare with surface water]. Groundwater Divide The boundary between to groundwater basins where the water on one side flows toward one basin and the water on the other side flows to the other. This is similar in concept to a watershed divide or the continental divide for surface waters. Half-life (t½) The time it takes for half the original amount of a substance to disappear. In the environment, the half-life is the time it takes for half the original amount of a substance to disappear when it is changed to another chemical by bacteria, fungi, sunlight, or other chemical processes. In the human body, the half-life is the time it takes for half the original amount of the substance to disappear, either by being changed to another substance or by leaving the body. In the case of radioactive material, the half-life is the amount of time necessary for one-half the initial number of radioactive atoms to change or transform into another atom (that is normally not radioactive). After two half-lives, 25% of the original number of radioactive atoms remain. Hazard A source of potential harm from past, current, or future exposures. Health consultation A review of available information or collection of new data to respond to a specific health question or request for information about a potential environmental hazard. Health consultations are focused on a specific exposure issue. Health consultations are therefore more limited than a public health assessment, which reviews the exposure potential of each pathway and chemical [compare with public health assessment]. Health education Programs designed with a community to help it know about health risks and how to reduce these risks. Health Base Value (HBV) An MDH criteria, a HBV is the concentration of a contaminant in water that is considered safe for people if they drink water daily for a lifetime. HBVs have not undergone the state s rule-making process. 59

62 Health Risk Limit (HRL) An MDH standard, a HRL is the concentration of a contaminant in water that is considered safe for people if they drink water daily for a lifetime. Incidence The number of new cases of disease in a defined population over a specific time period [contrast with prevalence]. Ingestion The act of swallowing something through eating, drinking, or mouthing objects. A chemical substance can enter the body this way [see route of exposure]. Inhalation The act of breathing. A chemical substance can enter the body this way [see route of exposure]. MDH The Minnesota Department of Health. Medical monitoring A set of medical tests and physical exams specifically designed to evaluate whether an individual's exposure could negatively affect that person's health. Metabolism The conversion or breakdown of a substance from one form to another by a living organism. mg/kg Milligram per kilogram. Migration Moving from one location to another. Minimal risk level (MRL) An ATSDR estimate of daily human exposure to a environmental contaminant at or below which that substance is unlikely to pose a measurable risk of harmful (adverse), noncancerous effects. MRLs are calculated for a route of exposure (inhalation or oral) over a specified time period (acute, intermediate, or chronic). MRLs should not be used as predictors of harmful (adverse) health effects [see reference dose]. Mortality Death. Usually the cause (a specific disease, a condition, or an injury) is stated. MPCA The Minnesota Pollution Control Agency. 60

63 National Priorities List for Uncontrolled Hazardous Waste Sites (National Priorities List or NPL) EPA's list of the most serious uncontrolled or abandoned hazardous waste sites in the United States. The NPL is updated on a regular basis. NPL [see National Priorities List for Uncontrolled Hazardous Waste Sites] PFC Perfluorochemical, a family of fully fluorinated hydrocarbons. Plume A volume of a substance that moves from its source to places farther away from the source. Plumes can be described by the volume of air or water they occupy and the direction they move. For example, a plume can be a column of smoke from a chimney or a substance moving with groundwater. Point of exposure The place where someone can come into contact with a substance present in the environment [see exposure pathway]. Population A group or number of people living within a specified area or sharing similar characteristics (such as occupation or age). ppb Parts per billion. ppm Parts per million. ppt Parts per trillion. Public comment period An opportunity for the public to comment on agency findings or proposed activities contained in draft reports or documents. The public comment period is a limited time period during which comments will be accepted. Public health action A list of steps to protect public health. Public health advisory A statement made by ATSDR to EPA or a state regulatory agency that a release of hazardous substances poses an immediate threat to human health. The advisory includes recommended measures to reduce exposure and reduce the threat to human health. 61

64 Public health assessment (PHA) An ATSDR document that examines environmental contaminants, health outcomes, and community concerns at a waste site to determine whether people could be harmed from coming into contact with those contaminants. The PHA also lists actions that need to be taken to protect public health [compare with health consultation]. Public health hazard A category used in ATSDR's public health assessments for sites that pose a public health hazard because of long-term exposures (greater than 1 year) to sufficiently high levels of hazardous substances or radionuclides that could result in harmful health effects. Public meeting A public forum with community members for communication about a site. Receptor population People who could come into contact with environmental contaminants [see exposure pathway]. Reference dose (RfD) An EPA estimate, with uncertainty or safety factors built in, of the daily lifetime dose of a substance that is unlikely to cause harm in humans. Registry A systematic collection of information on persons exposed to a specific substance or having specific diseases [see exposure registry and disease registry]. Remedial investigation The CERCLA process of determining the type and extent of hazardous material contamination at a site. RfD [see reference dose] Risk The probability that something will cause injury or harm. Route of exposure The way people come into contact with a hazardous substance or environmental contaminant. Three routes of exposure are breathing [inhalation], eating or drinking [ingestion], or contact with the skin [dermal contact]. Sample A portion or piece of a whole. A selected subset of a population or subset of whatever is being studied. For example, in a study of people the sample is a number of people chosen from a larger population [see population]. An environmental sample (for example, a small amount of soil or water) might be collected to measure contamination in the environment at a specific location. 62

65 Saturated thickness The vertical thickness of an aquifer in which all of the available pore space is filled with water. Solvent A liquid capable of dissolving or dispersing another substance (for example, acetone or mineral spirits). Source of contamination The place where an environmental contaminant comes from, such as a landfill, waste pond, incinerator, storage tank, or drum. A source of contamination is the first part of an exposure pathway. Special Well Construction Area (SWCA) Minnesota Statutes, section 103I, subdivision 5, clause 7, grants the commissioner of health the authority to establish standards for the construction, maintenance, sealing, and water quality monitoring of wells in areas of known or suspected contamination. Minnesota Rules, part , detail the requirements for construction, repair, or sealing within a designated SWCA, including plan review and approval, water quality monitoring, and other measures to protect public health and prevent degradation of groundwater. Stakeholder A person, group, or community who has an interest in activities at a waste site. Superfund [see Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and Superfund Amendments and Reauthorization Act (SARA) Superfund Amendments and Reauthorization Act (SARA) In 1986, SARA amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from substance exposures at hazardous waste sites and to perform activities including health education, health studies, surveillance, health consultations, and toxicological profiles. Surface water Water on the surface of the earth, such as in lakes, rivers, streams, ponds, and springs [compare with groundwater]. Survey A systematic collection of information or data. A survey can be conducted to collect information from a group of people or from the environment. Surveys of a group of people can be conducted by telephone, by mail, or in person. Some surveys are done by interviewing a group of people [see prevalence survey]. 63

66 Toxicological profile An ATSDR document that examines, summarizes, and interprets information about a hazardous substance to determine harmful levels of exposure and associated health effects. A toxicological profile also identifies significant gaps in knowledge on the substance and describes areas where further research is needed. Toxicology The study of the harmful effects of substances on humans or animals. Transmissivity In hydraulics, this is a measure of the rate at which water moves through an aquifer or a defined portion of an aquifer. Tumor An abnormal mass of tissue that results from excessive cell division that is uncontrolled and progressive. Tumors perform no useful body function. Tumors can be either benign (not cancer) or malignant (cancer). Uncertainty factor Mathematical adjustments for reasons of safety when knowledge is incomplete. For example, factors used in the calculation of doses that are not harmful (adverse) to people. These factors are applied to the lowest-observed-adverse-effect-level (LOAEL) or the noobserved-adverse-effect-level (NOAEL) to derive a minimal risk level (MRL). Uncertainty factors are used to account for variations in people's sensitivity, for differences between animals and humans, and for differences between a LOAEL and a NOAEL. Scientists use uncertainty factors when they have some, but not all, the information from animal or human studies to decide whether an exposure will cause harm to people [also sometimes called a safety factor]. Upgradient A location upstream relative to groundwater flow directions, or the direction from which groundwater is flowing. Volatile organic compounds (VOCs) Organic compounds that evaporate readily into the air. VOCs include substances such as benzene, toluene, methylene chloride, and TCE. Water table The subsurface layer below which all available pore space is completely saturated with groundwater. Other glossaries and dictionaries: U.S. Environmental Protection Agency ( 64

67 National Center for Environmental Health/Agency for Toxic Substances and Disease Registry (CDC) ( National Library of Medicine (NIH) ( For more information on the work of ATSDR, please contact: Office of Communications National Center for Environmental Health/Agency for Toxic Substances and Disease Registry 1600 Clifton Road, N.E. (MS E-29) Atlanta, GA Telephone: (404)

68 Appendix 1: Figures 66

69 67 Figure 1 - Location of 3M Sites and Major GeologicFeatures in Washington Co., MN Minneapolis Legend c::j Washington Co. municipal boundary St. Paul groundwater divide -- bedrock faults - bedrock valley Miles

70 F 0 F F F F F F F F I! I I I I I I I I S-0 F F F F F F F F ~ 0 Perfluoro-octane sulfonate (PFOS) F F F F F F F F I I I I I I I II \ F F F F F F F 0 0 Perfluorooctanoic acid (PFOA) F F F O F I I I < 0 F F F Perfluorobutanoic acid (PFBA) Figure 2: Chemical structures of the major PFCs detected in the groundwater of southern Washington County, Minnesota. 68

71 69 Figure 3-3M-Woodbury Disposal Site Well Location Map Monitoring well Recovery well 0 Observation well Barrier well W 3M-Woodbury Property Boundary Approx. location of PFC disposal areas Minnesota Dept. of Health - 10/6/09

72 70 A A' irie du Chien Legend - Quaternary St. Peter Prairie du Chien Jordan - St. Lawrence ille ' Area of isolated "pocket" of PFBA in the Jordan (Fig. 14) Vertical exaggeration = 20x Figure 4 - Cross-Section Across Highly Faulted Zone This figure shows a cross-sectional view of t he bedrock along a transect (blue line in map) from Cottage Grove near Ravine Park and trending eastsoutheast to the St. Croix River. Many bedrock faults (shown in red) have disturbed t he geology in this area, bringing different bedrock units into contact with one anot her. This may have allowed PFBA to move from one aquifer to another, creating what appear to be isolated "pockets" of contamination when viewed on a map (such as Fig. 9}. The arrows on the cross-sect ion view show a hypot hetical pat hway that PFBA may have followed t hat would allow the contaminant to migrate from the Jordan into the Franconia and back into t he Jordan again. Prepared by MDH - 8/26/09

73 Figure 5-3M-Woodbury Disposal Site Bedrock Legend L- - 1, 3M-Woodbury Disposal Site D Platteville-Glenwood D St. Peter - Prairie du Chien D Jordan Prepared by MDH- 8/5/09 This figure shows the uppermost bedrock units that underlie the 3M-Woodbury Disposal Site (I.e. the first bedrock unit beneath the unconsolidated soil, sand, and clay near the surface). Note that from northeast to southwest across the site, successively deeper units are the " top" bedrock layer. The areas where the Prairie du Chien and Jordan are shown coincides with a major burled bedrock valley. 71

74 72 CJ) Col 3 "0 i5" c Col <D 1/3/2007 r \1 PFBA, ppb o o ~ ~ N N w w ~ ~ ~ ~ m m ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ p v 'ar 213/ ~ ~ ~ /~ ~ 413/2007 l~ l ~ I ~ ' ~ < 513/2007 ' ~ ~ ri,j,,. ~ (I) ~~ I ;~ ~ 713noo7, ~ \ ~ 813/2007, r ~ n '.., 913/2007 j J 1 ~ 1013/2007 -, t)( ~ ~ 11 /3/2007 i -~~l l ;! i 12/3/2007 ~ I ~if V 1/3/2008 2/3/2008 ~ /2008 5t3/2008 6/3/ /2008 8/3/ / / /3/ / / / / /2009 5/3/2009 1/ 'I 1 :\ \ : 1Jl r t ~ \ \~.. 1l} L_UJi ~_J._l_L_L_L l_l_l j 'TI ca c co m "'C 'TI llj J> r a> < a> (/) :::J () 0 ::::: I» tc a> G)... 0 < a> :: c :::J 0 "0 I» :E ~ Y' 1\) ! I 1\) 0 0 <0 I I ' t I z ~ ~ co<»~m~~wn~ 0?

75 Legend Figure 7- PFBA in the St. Peter.. PFBA >?ppb PFBA = ppb PFBA = ppb PFBA = ppb - PFBA < 0.1 ppb - PFBA not detected bedrock valley 0 sampled well Note: in areas with no color coding, there were no wells in this aquifer to sample and insufficient information to fill in the PFBA concentrations, or the St. Peter is not present in this area. 73

76 Figure 8: PFBA in the Prairie du Chien Legend.. PFBA > 7ppb PFBA = ppb PFBA = ppb PFBA = ppb.. PFBA < 0.1 ppb.. PFBA not detected.. bedrock valley -- fault 0 sampled well Note: in areas with no color coding, there were no wells in this aquifer to sample and insufficient information to fill in the PFBA concentrations, or the Prairie du Chien is not present in this area. 74

77 Legend Figure 9: PFBA in the Jordan PFBA = ppb PFBA = ppb ~ PFBA not detected - Fault PFBA = ppb ~ PFBA < 0.1 ppb Bedrock valley 0 sampled well Note: in areas with no color coding, there were no wells in this aquifer to sample and insufficient information to fill in the PFBA concentrations. 75

78 Figure 10: PFBA in the Franconia Legend PFBA = ppb PFBA = ppb.. PFBA < 0.1 ppb PFBA not detected - faults bedrock valley Note: in areas with no color coding, there were no wells in this aquifer to sample and insufficient information to fill in the PFBA concentrations. 76

79 77 PFOA, PFOS AND PFBA SOIL SAIVPLE RESULTS NORTHEAST DISPOSAl AREA 3M WOODBURY SITE WO<XlBURY MN Geoprobe Boring loca1ions Cauours Trench Area Dtsposal Area Boundaries...,,... Not detect"..d at 01" above h! I.Jma of Ouanwtlon Source: Weston 2008a

80 78 07P e Figure SColltll- Source: Weston 2008a SOIL SAMPLE RESULTS FOR FORMER MAIN DISPOSAL AREA AND MUNICIPAL FILL AREAS 3M WOODBURY SITE WOODBURY, MN

81 Figure 13 -Areas Where Multiple PFCs Were Detected Legend - Area with multiple PFCs - Bedrock valley 0 Private well with drinking water advisory e Non-community public well with PFC levels that require treatment 79

82 Figure, 14: PFOA De,tections in Cottage Grove PFOA Conoen1ration (ppb} o.so 0 O..S e W I!IJ ~nopfq\ 80

83 81 Figure 15: Secondary Flow Paths in Fractured Rock This figure from a tracer study perfom1ed by Shapiro (2008) iijustrates the concept of primary and secondary flow paths in fractured rock, like the Prairie du Chien in w ashington County. The majority of contaminants in the aquifer quickly move through the primary (or "fast") flowpath. creating the firs t.. pulse" of contaminant migration (shown as 'Time I"). This is followed by slower movemem of the remaining contaminants through the secondary (or 'slow") flowpaths, resulting in a more dilute but longer lasting plume (shown as.. Time 2").

84 Appendix 2: Tables 82

85 Table 1: Initial 3M-Woodbury Disposal Site Monitoring Well Data 1, (in ppb) Sample Location 2 Aquifer 3 PFOS PFOA PFBA PFBS PFHxS B1 CJDN B2 OPDC ND 6 ND ND ND B3 OPDC B4 OPDC MW-2 OPDC NA 7 NA 118 NA NA MW-3 OSTP NA NA 3.25 NA NA MW-5 OPDC NA NA 1.7 NA NA MW-7 OSTP NA NA 1.72 NA NA MW-8 OPDC NA NA 5.09 NA NA MW-11 OPDC NA NA NA NA CWM CWD NA Notes: Values shown in boldface type exceed MDH drinking water criteria. No criteria exist for PFBS or PFHxS. ppb = parts per billion PFOS = perfluoro-octane sulfonate PFOA = perfluoro-octanoic acid PFBA = perfluorobutanoic acid PFBS = perfluorobutane sulfonate PFHxS = perfluorohexane sulfonate 1 Data are from Weston (2007a). Results are average values calculated from two samples from same well collected on same date 2 Well locations are shown in Figure 4; B = barrier well; MW = monitoring well 3 Aquifer abbreviations: CJDN = Jordan, OPDC = Prairie du Chien, OSTP = St. Peter 4 Combined discharge from Woodbury pumping wells 5 Non-contact process water discharge from retention pond at 3M-Chemolite Plant 6 ND = not detected above the method detection limit 7 NA = not analyzed 83

86 84 Table 2: General Results of 2007 Private and Business Well Sampling, results in ppb Aquifer No. of Wells Sampled No. of Wells w/ PFCs Detected Max. PFOA Max. (% wells) 1 PFOS (% wells) Max. PFBA(% wells) Quaternary 12 9 ND ND 2.8 (75%) St. Peter ND ND 2.5 (73%) Prairie du ND 3.3 Chien (4%) (94%) Prairie du 5 3 ND ND 2.3 Chien (60%) Jordan Max. PFPeA (% wells) (17%) (7%) (11%) (20%) Max. PFHxA (% wells) Max. PFBS (% wells) ND ND ND ND ND ND (5%) (20%) ND ND Max. PFHxS (% wells) Jordan (7%) (1%) 4.0 (71%) 0.3 (14%) (6%) (1%) (1%) Franconia ND ND ND ND ND (30%) (2%) Unknown (18%) (1%) 5.6 (94%) 0.42 (51%) (22%) (2%) (2%) Multiple ND ND (62%) (24%) (14%) 0.1 (5%) ND 1 First number is maximum concentration of the compound detected in any well in the designated aquifer, in parts per billion (ppb). Number in parentheses is the percent of wells in that aquifer in which the compound was detected at any concentration. 2 ND = not detected above the method detection limit in any well in this aquifer ppb = parts per billion PFOS = perfluoro-octane sulfonate; PFOA = perfluoro-octanoic acid; PFBA = perfluorobutanoic acid; PFPeA = perfluoropentanoic acid; PFHxA = perfluorohexanoic acid; PFBS = perfluorobutane sulfonate; PFHxS = perfluorohexane sulfonate ND ND

87 Table 3: 3M-Woodbury Disposal Site Groundwater, (in ppb) Well Date PFBA PFPeA PFHxA PFHpA PFOA PFBS PFHxS PFOS B-1 June ND March B-2 June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND B-3 June ND March ND B-4 June March MW-2 June NR ND March MW-4 June March ND MW-G June ND ND ND ND ND ND March ND ND ND ND ND ND ND MW-H June 2007 ND ND ND ND ND ND ND ND March 2008 ND ND ND ND ND ND ND ND S01JS June 2007 ND ND ND ND ND ND ND ND March ND NR ND ND ND ND ND S01PC June ND ND ND ND ND March ND ND ND ND ND S02DR June ND ND ND ND March ND ND ND ND ND S02JS June 2007 ND ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S02PC June ND ND ND March ND ND ND ND S03JS June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND 85

88 Table 3 (continued): 3M-Woodbury Disposal Site Groundwater, (in ppb) Well Date PFBA PFPeA PFHxA PFHpA PFOA PFBS PFHxS PFOS S03PC June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S04PC June ND ND ND ND ND ND ND March ND ND ND ND ND ND S04SP June ND ND ND ND ND ND March ND ND ND ND ND S05JS June 2007 ND ND ND ND ND ND ND ND March 2008 ND ND ND ND ND ND ND ND S05PC June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S05SP June ND ND ND ND ND ND ND March ND ND ND ND ND ND S06JS June 2007 ND ND ND ND ND ND ND ND March 2008 ND ND ND ND ND ND ND ND S06PC June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S07JS June 2007 ND ND ND ND ND ND ND ND March 2008 ND ND ND ND ND ND ND ND S07PC June ND ND ND ND ND ND March ND ND ND ND ND ND ND S07SP June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S08JS June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S08PC June ND ND ND ND ND ND ND March ND ND ND ND ND ND ND S09JS June 2007 ND ND ND ND ND ND ND ND March 2008 ND ND ND ND ND ND ND ND Data from: Weston (2007b) and Weston (2008b) ppb = parts per billion ND = not detected NR = not reportable 86

89 87 Table 4: Range of PFC Concentrations in Cottage Grove City Wells (in ppb) Well PFBA PFPeA PFHxA PFOA PFBS PFHxS PFOS No ND ND ND ND ND ND ND ND ND ND ND ND ND 0.07 ND ND ND 0.14 ND ND 0.07 ND 0.56 a ND ND 0.21 ND ND 0.07 ND ND ND ND ND ND ND ND ND 0.17 ND 0.07 ND ND 0.06 b ND 0.05 a ND ND 0.16 b ND ND ND 0.07 ND 0.06 a ND ND 0.09 a ND 0.14 a ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND PFC = perfluorinated chemicals Notes: ND = not detected above the method detection limit ppb = a parts This per compound billion detected in only one sample from this well since November 2006 b This compound detected in only two samples from this well since November 2006

90 Appendix 3: Public Comments 88

91 A draft version of this Public Health Assessment report was released for public comment on August 25, MDH received written comments from State Senator Katie Sieben, the Minnesota Pollution Control Agency (MPCA), and 3M Corporation (3M). The texts of the comments are included in this appendix. Sen. Sieben s comments primarily focused on the unknowns regarding past PFC exposure levels, possible long-term health effects, and the need for continued monitoring of water quality and public health in the affected communities (Sieben, 2010). The MPCA comments focused primarily on differences in interpretation regarding the adequacy of the monitoring well network at the 3M-Woodbury Disposal Site and the source PFCs (other than PFBA) in the Langdon-River Acres neighborhood in south Cottage Grove (MPCA, 2010b). These comments were addressed in the PFC-Related Investigations at the 3M-Woodbury Disposal Site and Evaluation of Impacts to Groundwater sections of this document. Specifically, the MPCA comments were addressed in the following locations: 1. Potential Source of PFCs Near Langdon Neighborhood these comments were addressed on page 28 and by the addition of Figure Adequacy of 3M s Monitoring Well Network at the 3M Woodbury Disposal Site these comments were addressed on pages 18, 29, and 41. 3M s comments addressed a number of areas, but primarily focused on: differences in hydrogeologic interpretations, the adequacy of the monitoring well network, 3M s PFC waste disposal and reporting history, PFC toxicology and the potential for human health effects associated with PFC releases from the 3M-Woodbury Disposal Site, and the recommendation to extend city water to the most contaminated neighborhoods (3M, 2010a). These comments were addressed, as appropriate, throughout the document, but primarily in the PFC-Related Investigations at the 3M-Woodbury Disposal Site, Evaluation of Impacts to Groundwater, Exposure Through Private Wells, and Public Health Implications of PFC Exposure sections of this document. Specifically, the 3M comments were addressed in the following locations: 1. Summary section, Introduction heading these comments were addressed on page 4. Reference to possible exposure to air emissions were retained in the introduction as a possible exposure pathway since dust and ash (generated during waste burning) could have contained PFCs. 2. Summary section, Conclusions 1 and 2 3M s comments are more narrative than editorial and largely go beyond the scope of the summary section, MDH believes the caveats included in Conclusion 1 are sufficient to explain the uncertainties associated with past exposures. 3. Summary section, Next Steps these comments were addressed, where appropriate, on page Introduction Section the suggested historical information has been incorporated on page 6; other comments have been addressed, as appropriate, on pages Background Section, Site Description and History these comments were addressed, where appropriate, on pages MDH does not agree with 3M s hydrogeologic 89

92 interpretations, as well sampling data clearly demonstrates the contaminant migration pathways described in this section. In addition, a recent minor reduction in pumping rates at the site has resulted in migration of PFCs to not only the Prairie du Chien, but also Jordan aquifer in downgradient monitoring wells, contradicting 3M s assertion regarding potential for contaminant migration into that aquifer. 6. Background Section, PFC Analysis this comment was address on page Background Section, PFCS in Drinking Water the suggested clarification regarding hazard index calculations has been addressed on page Community Well Monitoring the suggested clarifications were made on pages 12 and 13 and figure 6; MDH notes that despite 3M s assertion regarding the data shown in the table on page 13, there is almost no difference between the average and median data. 9. Private Well Sampling these comments and suggested clarifications were addressed on pages 14 17; MDH disagrees with 3M s hydrogeologic interpretation and assessment of the adequacy of the monitoring well network. 10. MPCA- 3M Consent Order for PFC Disposal Sites the suggested clarifications have been made on pages Remedial Options for the 3M-Woodbury Disposal Site the suggested clarifications were made on page General Regional Issues MDH and the cities of Woodbury, Cottage Grove, Lake Elmo, and Oakdale have expended significant resources evaluating the citing of new city wells to avoid the PFC plumes, or minimize the levels of PFCs in the new wells. This additional effort would not have been necessary except for the presence of the PFC contamination. 13. Community Concerns 3M s comments are not accepted, as the purpose of this section is to identify community concerns, which are addressed by the document as a whole. 14. Evaluation of Environmental Fate and Exposure Pathways, Introduction these comments were addressed, as appropriate, on pages Evaluation of Impacts on Groundwater these comments were addressed, where appropriate, on pages 23-26; however, MDH does not agree with much of 3M s hydrogeologic interpretation. As 3M notes in several places in their overall comments, the groundwater extraction system has been operating for over 40 years and presumed to be capturing all of the groundwater at the site, yet the PFC groundwater distribution documented by the sampling of hundreds of wells clearly demonstrates PFCs have migrated away from the site and do not follow a simple regional groundwater flow direction pathway, but instead are strongly controlled by small- and large-scale structures in the bedrock. In addition, a recent slight reduction in pumping rates at the site, which 3M s model showed would result in no loss of PFC containment was followed quite rapidly by detection of PFCs in monitoring wells not previously contaminated, suggesting that there are significant flaws in 3M s groundwater model and hydrogeologic understanding of the site. 16. Exposure Through Private Wells these comments were addressed, where appropriate, on pages MDH notes that as several additional well advisories have been issued since the original draft of this report were written, it is appropriate to retain language regarding the possibility of increased PFC levels in private wells. 17. Exposure Through Other Pathways these comments were addressed, where appropriate, on page

93 18. Public Health Implications of PFC Exposure 3M is correct in pointing out that this document only summarizes a small portion of the scientific literature on PFCs, as is appropriate for a document of this nature. The reader is referred to the ATSDR draft Toxicological Profile and the review paper by Lau et al (2007) for a more thorough review. The remaining comments were addressed, where appropriate, in the corresponding sections of the document. 3M s comments are also attached below if the reader wishes to peruse them. 19. Summary of Human Exposure Information A review of all available studies on PFCs is beyond the scope of the document. Modifications where appropriate were made in the corresponding sections to address 3M s comments. 20. Child Health Considerations the suggested clarification has been included on page Conclusions MDH does not agree with the suggested changes in 3M s comments. MDH cannot determine whether 3M s past disposal practices were legal. It is appropriate to discuss all possible exposure pathways airborne dust and ash were almost certainly generated at the site in the past and were very likely contaminated with PFCs, posing a possible exposure pathway albeit one that cannot be evaluated. MDH staff observed evidence of trespass on the 3M property, so direct contact with contaminated soil (and in the past, PFC waste) was a potential exposure pathway. The comparison of 3M s workers (a small population of primarily healthy, male adults) to the general population is not appropriate. Without adequate information regarding past exposures, MDH cannot make any conclusions regarding possible health effects of those past exposures. 22. Recommendations the language regarding the trespassing issue has been modified. MDH does not agree with 3M s comments regarding the other recommendations. MDH has long stated its preference for municipal water over individual filter systems, where feasible, to address drinking water contamination. MDH does not agree with 3M s hydrogeologic interpretations or assessment of the adequacy of the monitoring well network. 91

94 KAT1.ES~!fl... v Tli'~nn ~.1!J ~ ' IU ltlt.dnl»."' Of \It 1 (AUI'f ~~~.l. lim :t h.a\.!"-~ Ml'G llill'i ~~,,.;,) ~ ;..... t:.u,...,.,... t... ~>JUJou Sqltt:r11b..:r 29,2010 Site A (,,;e<;so'icol and COrtiUIUJllOu ljru l )tburl..:.~'~ht Dlll:Jr1mc:ot of H~ l etl P 0 Box 64'.nS 6:!.5 Robt!rt S IJ'Oet ~1'111 h,, Poul, MN 5) l6-hjiij7s Senate_ s~ of Minnesota To Whom lt May Co rtl~ l! I ~ \.l.ri11ngan tt rm: Lo tb.: pubiicjfbofl oi"pertlul"mchc;rli 1 Cont. m"l\ationm Southern Wa.~in f>n Cc 11'11)'. c llcf'll Dal.ul.l Cowtt). UJtll Su~ul! RaJ1~')' Co...-.Ly, \{j nn~ota..." J Pr c~t h. the uppx1muty fcx Jlllhlic oammmt 1 m'l I} lil4lp.llt at'kl. JJII'n~~.JL~ the "'\rri.. und :rc"!'learch thil1 hns been dnne to C'\'nluacc tl~ lrcallh dlatos nf PfC" c;100t~innuoo JDd i: 'd thai swnc l!~ca.li l) rl to..:. nlinlaj rnlr, the r'llture. lt &S dt.3 L, n..: a!ler n=-.tdms tile rcp!'l1, ttmt tl ~Ill cff~t r-c a.tlfclltly unl.no'~ t lli l'ql0(1 cites St.'\1Cfn1 S'tutik., talrng pi.:jce nnw nne! cxpo:t~lto he cnmp1ct.:d in chc nc:tt c~ }~ 1 ~ncct MDJ I {I) monic or tllc51c ">{ud iet~ w,j tsllottt: tlrc 1\.':.ulb,nth.MioDCSot:ul!. us ~lill ~ ebuy'n.. 11mlahlc.. l.tlso thlflk It is ur~ p tunllu d Llluent~:tte he tw~ r unki)o~-n ~d nn ub!cor;c ofbcaltll IJiloct'i. I """" d'i~in1cd t(l S«lcx:ll mc..lta oo crat;e ollhe n."'pud staflng llrallcjw PI'C levels ill tbc-l:u51etn rudro ore unlikely._, n:qrh in.-h~e "I!Pltb dli:as \J1'4 only '\.\I! not now t~al to Oc: lnl~. we aloo doo 'L lnnw ll PfC\'IuU.'> le~ ~of PfC ~ m 1hc u ul\.'1' T1 rq>tkl stak-s Llrar bcrch, ne h:n!j.i'll Qf1im-e lotol re<idcots wen: Cl:JXI alto PFCo; h.mu&b their dnn inr; \\ La IS u..nk:nuwu. Ark!. -lt ~ a.lsu ~!>tbltl rat the lc\-.::1!> m the 11J t>und~ alll WCt C lugbcr tkm cum:miy clr:lo.c1c\i " r1 S irnpor1nnl th:lt II. e lit~ \I ~j t nd tnncinue to keep the hcaltlt ol MJJI!ICMJl.DI:~ lorcfn1111m o;1ar mmd,., lhan you. a~ li1r th~ opputruttn) lu cunuocjtl. llouk!rm~.ud 11, cun hnm~ to "'('Irk \\ atlr \IOH oo thu; amport.3ni i~ S OC~n:ly. /{ikfo~ Krrlie Sieben Slalt! Su11114w

95 At mcclinn'>1th M I~A Supcrfu1uJ ~fhnd numagcmcll1 gn l'kl.-em~~ 2. 2(11(1 Kita Mc:sSJ ' u~:rv-uo 1 ot the Ml)Jl :tc A 5CS~J~ t t nnd '-'I ultm OC1 Urut. ~ u~tc-j a lanlu.: 1101 ol 5 \'croll Ml"CA mmmc:nl ii'\.:j!ill'dinl!, the toll Dmft PuOlu: I k.t th As:sc~mm t (PfiAl t C'flllJOC'ocl~"'ll teal Cv1L :unin:uion 10 :S<.outhcru Yt usluustou C<lunty. otthcm D.Jkol3 Coo1,1) tu~ [lull>: Run ~ ) Co1tnl), Mumc:S<Kn. The follu'o\ iog clnn fio.'"ion i distttl> ioo'd.aborntion of!i&:n"r.ll ti>ca tl!ltrllb that Ml t A.wbuuncd durmg I ac ufit tal publ&<: c01omcn1 pcnod lltal mdc\1 on(); obcr 12, 2010 I he Dr.ttl \ fco..-u cd oo ~he 3M Woodlx.tr) mllp I ~ te t"ite) 1J'CA' comment on the 1 HA. dntcd )Ctul\..'"f iodudcd bticf r :)poe t~ ID t \D ls~cs lltal w~:r dt ~'\1 by M I Jfl (I) \ pment I oun:c' of PF ~<onuumn.ltion ncnrehe f lt'km ncill,hlxlrhood in -.. ttilgc' CJ1o\c tmd {2J l he tuio.'\:ju:tc) ol 3M'!i ntuluioiuts wdi111..'11work. utlu:...:st J\fk'1 rccct YU18 MI'CA s :tl l~'l' COJIUl){'ttts.. MOH!ll.lll ~;nu\.'\1 n 11:ctm1cal sunttn:tf'!> " tl c 1 \ i c urxl utxmued iho MP "'A 1 hh; do WTX'nt i~ M PCA 's n.--spoi\sc 10 the M DH lcdun I wntnnt} 1~b.:, td ('()J t ~1t i UIC'S lhc M 1 CA ~'OSiltOn onlltc 1W(J 1 In DcccmbN 2002~ u laq; rm: tx: um:d at f1 Nl.llrth l'bsll~:~. a m.m~factunt~ Ja~. Ji tl) IIX: ted t'r i 1 ~ely one-h. 1f rr.llc ~ t ol th I n Ikon cilt}loomood f he tire re ir d 1h: 3ppl..:.tltoat ufuptlinxittla1d) 4000 t,?lklm ofctu2 U (IJf '-contnimng) fircfiglt mg fi)3jn In onkr to ~.\ti~ 1i h it. Apr.«11nutd) 20 tire dcp lrtjll('ni.s ~nde(l to ~tx: Up orth I' sties fire. Rc,)f,l iii die 1 lh:tl most of the (~Um used ut the fire wa~ man..1 uclun.-d b~ \M, and b:t~-d on 3M Mat~ ttal Sufd) OJ :-thect5, the fc l co1 tined nppn ~ m:ucl) 0 S-1 PFO s 1 :Sec M SO ) J) umrot i tn sh :w~d that the fuam r.ut Stnll}m;ud ofl Ill.: Up l)ttb projx"fl) nnd mill u stonn dr.asn. a d1tch and n pond south ofthcf. i it)( I i twe) As ~un ofdle Jt'ccnt \\amlc regunji~ I'I C~ in g.rowto;h a c1 an 11>\; custmt mc"'ropohwn u \."'l. locnl I illl.llor muj other noicjal:s c:\pn::i:;c"';l au~nt.ll th;at the Up North lii"'c' 1\lld bllvc asu cd!;nul'ld' 1C'I d.:ur well conutmmaucm llllhc are-;1 ([t r~po1 C' U> r~ucsts from l a olli~.: tl the MI'CA md 1Jcd.. Ctx' ol'it5 mullt site cnntn11:1ms to cond~'t 11 hmited ln\"t"c~tigntjmt. nd cui I oil, Ill ::C \\ IC'f nd cdllltcoi npjcs II the\ tdn I) 1)f p North l'l ;zsti~.: (I I~ II C) fbe tj '' omh dma 6hO\\ tl\ C \\ cre dct«lcd in ll hr~c rncdt but nt concc.nr t<tll. bdo ' c.um: p:nxl 1 hculth ha..-1ct1 '-l:llldan!s (fubl.:s, 1..'11Qll) 1 1 OS mtd l 0 fllx \ \.".1'1:' the PJ < J w11h the,-~c t ~ om II ruti 'fl II olil otld cdimcm. " ilc I~ pond \ ll'-'1' I l \\C'IC' ltlj;h. Ill ] 1 1 BA 93

96 and 1'10.\. ~U'CJ\ u lw~ eatiun!l at Ollx'r knu'"n l in: l i t:;hlin~ loam sa~"!! h:s\~ sbo..,nlh:~ tl't OS u00 l'l'lhs lll tontn II Ill,.tii,IIIIUiill.."\1 j:i UII~";dCf tlabk -1: 11- \\AJ JA $11~1.,\\ p&n of the limi1~d Up.:-ictth im-cs1igati;:m, MPCA ~.onkij. 1< r alw umpic.j IUur irri ~al,.,.. "'t II~ lo.:utc:d sou~-ntlil~~n.. iml l from lhc l r S llfth jxc«rt~ rigu~: Wah:r 'ilm;-1.-l!r, m thut' ltrttuloo l 'dl conu. ned dckctl~lffi o.ff4:,cr;ai PH.:S {mu1 I) 1'1-'HA ;ml) f'to,\llfimi"'''i< l d. vo I ctlll tmcd S1Mt.lards (Tables, o!llwii. I' I Jl'\ au.j J H M <~«c:ntrju:on~ 1n ~..e ".:II wmplc.s otrc: ~,;cc i~ ~i1h I r-ep.~nal d!ilnbmt... onof[>l Cs 10 &:roun~at~:r. Rue-d on lh!' limilc:d imcstisation nc.:z lbc l p l'unh ~. anj ca cbu I rom cthcr f~figh1ing I.:no ~lo 1 q;., MIIIIICII~'t: ~ SC. 1' ~1 t\lrpji1j. MP<.' \ &tmnin~: il l.h.c lh~: C lot>s H loam ck'd in thr l!p Ncnh fire tl(d not apr.. -:~, K> b: m1ucr 0111 '" " "'I P~C Jlruui!J..:;~(t cou!ilm ft.tl!\ 11 1hc fll(';l. fun! ~IliON', tk l'f~ cantmltrutc\l ~'t'lls 111 1be Lm~,n n.: l!hb ub.'kkl do n.:lt ~ar to br irup:.:ted by PFC.s fr~m W l p 1\;~rtb I irditbtl f~, I be fa::! ti;jt tho: Iii('""~ ;a~~ ~ um: &:\.:nt. lin: 10'>' c :on..-,:r..trjijuns or l ol t f{ and 1'1 1-h~ 1ft the l.nn~&;m nc ~ho.. Iik-.N \\el l;,.. u.j the l l'l!fllllicnt ~ioo af the wrll~ rcbth't' to 1 CI.Ju It foom rd:;~~ fn m th~ l p ~.11 th f.n: a~ all n ilkrn:r that chr Up NJXth tirc' ~as nat ullr:l) SQHI 1: icf f'l C ~'COI.dl1'lh tlfcip llllhe<l." lo\"11' Sunii,JII}, I ic' I J'!'i'Oll ron- "' IS IX!11t flr:l\ SOUn;C for 1 ohser."'rd I' I C runt.jrnin~l. n in UIC' Kl\ tr \~ rr. nril!hl>;)rlt.jod "'"-fls. J \t wbfl1 f1tltl~ 10 1/l: \ 1f'C.\ 1'1-.1\ lllc1i lf.iiic II lui (If lnlllt IIUI i.;u tah lui f'i C V.llllt' dt11..:x;.j.i JII II'C ':Site.fl ~,\ fi.cs in.u..011c tholl from l~bllt.o I %J. J M di1p..'si:d apprv\imlllltl) l t.,ooo pal~ns ofhydrctlq. ri.:: u.ul sltul~c und lar.lml the nortjt,as1.lr Jk'Stl.. Ji l'j.. Jl ~he""" l l c stud~ uud t.s "(TV d~ro~t"c< I m tmcst:lnr lined (~< ~ llllth't' tx"dn..:q llll'limcmtw sian) 1: 11.-J trcnthl'l. 3~1 m:o1 d:s!them tlj.at tlu: PfC -.Q01J rur.f! ncid 1.1r WOI.Slc \\'J.'S pij~x~.i ir.1n the Nl Ut~OI Ar~ 01$ n b1:ll.: liqu~l Jlol~t~"C'f. W1llt\'Cs.11_allun4tt )t-:~r.~o la!cr fullfi:ilh~ t most oft~ :..ctj slud~c and tiir ln.1 mis :11~ ltt tll the trcndles nnr.i t~!ji ir:to the oquifm nn;l ~r..:~y lllt\'c movt\l n~;~y from the S' tc bcli rr: the Nrril'r wells "'~ ins:::~ll~-d. Ml'CJ\ Iiles m:!iclllt tlmt bifh.:cm:rn 11111mu of l'fcil\~ found in rcnbmimted Ill II al thr m. un d.:spos;tl urn. Oruun&malcr dojia 'ill'" \hill ul k.ut eh.!hhhffm J t J'I., Ull.'imhr.::: l'fos oud l'flb.s, t.:"~ t~ dcteo; Ifil l 1t:e(~ hltle j (luml'lll\} 'I b: ntrnl cf 'I C s;rounjwllln rontammatico d""'lli!jl"lu:nl (1.<'- scuth nn<l ~~~~~> "n1 1iurulhc W~ ""'Uf) ik tvs.ll It~ I,lt,p!o )~ 111 1' h.coi - wrtf t thr )M C,l!I;IC,C <11TI'fi.' fitjhl).,pccificllll)'. t\li>enrml«l Yoeii5(M\~ -1 w MW-S) locatcj oo then~,,;k orthr IJ.t:l.il) ', and thcjrl..:~t up~mj~ifl or ~1101\D <li~lllllr a~ Ul th" OJJlil~ (till"'" Ca.:UJ~. ('.VIibil ri\'vi!l\!<1 PFQ:\ aoj l'f{l'i c~r.jtk!n (f ctnre) l~r n:~nce(i(p I c ront.untnr.ti on in~~ rnooij onn& wrl i\ coas1jk':lt -..t!h t!x tnlt:rprc'b1j<d that thr \lioodbl::) lluposll \Itt' is tb: sour~ I«~TJ;IorW PIC' ~:rou1uh, 1 ICT rontan:ntt-llll.ln The 1'1 C.. U1r JtSJ'OS.,I pract:~co:~.. u chr Site. the pn: ~ uilms ~"' Iller B:J..., Jm:tlion~ bnj thr pm;;:r.;;c ol bcdro:,.11 1~ ar.d bo.h'(d lt.khltcs, 11nd t.c re~l dr!llll'foii OG of PI C t:jv<ii~"aler CO!tW'rl 1011 a!i ~pen tb::- co:~ccj:ttal n~cl lhlt the JM V. OO<Ihuty D:i~ \ ate r; ~ llljjijf ~r~ ou FC cmti'lllllllllttoo 111 the l.a:t,;joo wxl Rn'ft Atl'el nd~l-bjrhm"a ll11: n:hli\ 1: \ smj I numher of \\~JI~ lr-~ alot l! the boor~ I. o;ul ~ nonh of til: 1.s _.urul~ R"~ Aoc-s MJt:hbo:ntooll~ 11 co1t: pamon w the rewi"t'l} lol~ number,,rpm.a::~ vo~ '' m th~s.o: '"''0 n ~i!!hb: rtr.-.ods mo~y bw thr J t<~, nuj au~ abo s~ c~o~~ t!x- mll'tjirctllicn ol thc- tt.ll. r~.:rnll. b,,,..., 1,111 th.: '" ~ 111h 11nal"'" c MI"CA d:t :r=ll...:j t1111 tb: JM ~ o.: Jl u 1~ DlliJ1:15.11 'i1e t-. the: Jlf"'-uniii.JIII ~ ur.c: ft.lf ~ l'fc ~ atllrninollicil m thr lnngdonmd Ri~cr /lacs "dis. 94

97 MPCA ~;OC llc:nt 1 he I' 1\ 111 ludcd 1 CU ftllliciii 1cn.lc.IU ad lr CXtrt...1h.u '-"I) ~ rr. (IO~Ite r:~::mnoo: \\rllrmw SOb,.., iotrn;~ts1h h" h trllnsmiui\. \ IDih! Ulr/.1 inlh: rmiric Llu ChKI uqurlcr. Bllm:l on 3M's rn.'\ I~Uily u:jy.llld Oll,, r subu~ r lta.h. h\\1 ()tl ~r IOOIIIklfllll! n~lls t r.t\ '-o1l. an _ MW-S) rt OJ nto rhc tll'l In 1.1, i hmirt "'lb. H l nd U l oro:n lo 1 It I Z. \\Ill let ct udl B I mil) i::.1r~.. 1 the IITZ rfi ll:'l:5..:ro53~ tions). ~ern I Mf'CA nd;ru:rn le.l es ~ t UA s mt=.: chaa ;;~1 '5 rurwnt m~iil "...'l'll o:rworl conli 1r 100 u 1101 opci al i( rc- 'lulllint:o the lftz i the nn:-.1 Ll tj,!ir&dtntl frt~m 1hc tl pos~luruu As :1 OCIII~ t:, oc ''' M 1\ scoc liiciii cn r I'IIA '"'I " ~ ~d ~ 41!. rc rnrneruj. IIO r-frnii 1U I {r.r L"llprm ing lhe IH7. omitorinij, Ml' "A"s J~n:- 311, l.uiiiic:t~"''n: ro "lt1 l:o, ~ ~ >1 h K..:duc&: B.1rr1rr \',rill'uu rin taicsih Ml CA nnd tfjh \ ill rt'\'ic\-, l!nx.::t!.lw~cr chu 1!-.Jring lb: ini1inl t ~S% bmirr \\ell p.nnpin re.luc11on a1 lbc. c I 6-:tmr.ir,,.f:al Cond1IKIIIS. u, I &S till.' ' t:lll\.'lllof :t<ftlton.rl HIIUI ri \0. llii,nt... ~1 b: r~ ~Ill,\ r. I an~ funh I I Ultlp! ~lut111.1;.;, l hll I ;) ~ nj:7.jtcli d;~lln the harner 'Wicl pul pi ITdu.:tXtn roonuurmg '1\111 ht-lp II'CAf\U.JII.Jct~'mlilx- Jl l \1, 111 1::!1: r~u ~~~to il!:rrmc thco lfl Z ul hlrt5 ol1 ~nc IOfn '' II nch":d. I 95

98 KAT t: III IU. :; II ~P.'IY llata Sta:BT JK 31!1 Ccmtar st. P ul, "tn asoca Q-JG4-J~77 or (GS1) 7~7-GSOl (~ 4 ~oursj copyrj.gb't., ~999. rtlnna::;ot.a Kinin9 and eto.nufaot.uring ccapany. All rlgh~, ~~, Copying an~/or &Y.nlo~~ ~9 of ~h A inform~t.lon for the pu~po~ of p~op~ly utlllzlfto J~ produot5 i~ n11o~od p ~ovj.dod thal 1 1) t.tw lnfcn t.tc-1 1 cop1a4 in Toll IO':l,t~ no c:ll.,!i~ 1.11'11 " prior agrttt!:kmt. 18 0~'t. ll\6oc1 f ru11. JM, ~u)(} 2) nai~bqr tna copy ocr tho origtn~l is r osold or cthgrwi~ dl ~~rlbuted wltb t~~ ln~ti~~ uf ~rn l n~ ~ 'cof lt Lh~eun. f)iv:.fston: l.'1 SP~C1.Al.TY HATE:iDU.S 'f.iu\0!: N.utJ: J FC-602 LIOHl' WA7Dl('Dit ATC l'l.tis(tm) T ll NUKBF.ltfU, P, C,: 9U l ~ ~ ~ c~ s~~3~-10g72-3 <.:F-1, q cc-j!mlo-1 ~ n -1 XF l. XE l ZF l7B :2-0:ilA-0 2:7-0004! - 04?5 ~ z:-ooo:z-o!ics-6 Z# ls:iued: ~uabt r \ 7.,._Qg CP- 12CX.- ~LO-l CP-H0& or- l CXJ0-004~-4 X!' ZP-ooo2-ooel3-7 Zl!' ZF l9-B?.l' OC02 04lA h ZP-000:.! - 08!)9-J OO~S113S - 024BU-1 SUPERSEDES : April 08; 1999 OOCUH r~ : 1D-4l4E lnu l.o "F.t'J C,A,S, NO, 7732-lB !J 12 \. TIUt~l~ t (~12b~, 6122P RESIDUAL OBOAniC FLUOROCUEKl~ Tr ada';ucru t. 1 -!i SB-9 1 'h&~t'~t. 1 - ~ Unknown 1 11 co~,.. rn. of t.b..l S)CC4u.c-c. ~ ln eoapl1&n..:. lllt.b Lbe c:ht.ii..lcal notlflc tioo requiramon~~ oft-~. All epplic:4ble obomiool 1nqrodion~~ 1n tbis ~~ rial are! istod on tho Europo~n I nvantory of xist.1n.q ChgllicAl subst.acu:~ 4EIHElCS), or Aro QiiCO!Iptt. polyaar-a ~o<l'.oot DUII.UQ>I~ A' ti 1 J.!1-.,.d tjtl ~~ 96

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